Assessing the effects of bladder decellularization protocols on extracellular matrix (ECM) structure, mechanics, and biology.

INTRODUCTION: Acellular matrices have historically been applied as biologic scaffolds in surgery, wound care, and tissue engineering, albeit with inconsistent outcomes. One aspect that varies widely between products is the selection of decellularization protocol, yet few studies assess comparative effectiveness of these protocols in preserving mechanics, and protein content. This study characterizes bladder acellular matrix (BAM) using two different detergent and enzymatic protocols, evaluating effects on nuclei and DNA removal (≥90%), structure, tensile properties, and maintenance of extracellular matrix proteins. METHODS: Porcine bladders were decellularized with 0.5% Sodium Dodecyl Sulfate (SDS) or 0.25% Trypsin-hypotonic-Triton X-100 hypertonic (TT)-based agitation protocols, followed by DNase/RNase agents. Characterization of BAM included decellularization efficacy (DAPI, DNA quantification), structure (histology and scanning electron microscopy), tensile testing (Instron 345C-1 mechanical tester), and protein presence and diversity (mass spectrometry). SDS and TT data was directly compared to the same native bladder using two-tailed paired t-tests. Native, TT, and SDS cohorts for tensile testing were compared using one-way ANOVA; Tukey's post-hoc tests for among group differences. RESULTS: Effective nuclei removal was achieved by SDS- and TT-based protocols. However, target DNA removal was achieved with SDS but not TT. SDS more effectively maintained qualitative tissue architecture compared to TT. The tensile modulus of the TT cohort increased, and stretchability decreased after decellularization in both SDS and TT. UTS was unaffected by either protocol. Higher overall diversity and quantity of core matrisome and matrisome-associated proteins was maintained in the SDS vs TT cohort post-decellularization. CONCLUSION: The results indicated that detergent selection affects multiple aspects of the resultant BAM biologic product. In the selected protocols, SDS was superior to TT efficacy, and maintenance of gross tissue architecture as well as maintenance of ECM proteins. Decellularization increased scaffold resistance to deformation in both cohorts. Future studies applying biologic scaffolds must consider the processing method and agents used to ensure that materials selected are optimized for characteristics that will facilitate effective translational use.

Decellularized skin pretreatment by monophosphoryl lipid A and lactobacillus casei supernatant accelerate skin recellularization.

BACKGROUND: Bioscaffolds and cells are two main components in the regeneration of damaged tissues via cell therapy. Umbilical cord stem cells are among the most well-known cell types for this purpose. The main objective of the present study was to evaluate the effect of the pretreatment of the foreskin acellular matrix (FAM) by monophosphoryl lipid A (MPLA) and Lactobacillus casei supernatant (LCS) on the attraction of human umbilical cord mesenchymal stem cells (hucMSC). METHODS AND RESULTS: The expression of certain cell migration genes was studied using qRT-PCR. In addition to cell migration, transdifferentiation of these cells to the epidermal-like cells was evaluated via immunohistochemistry (IHC) and immunocytochemistry (ICC) of cytokeratin 19 (CK19). The hucMSC showed more tissue tropism in the presence of MPLA and LCS pretreated FAM compared to the untreated control group. We confirmed this result by scanning electron microscopy (SEM) analysis, glycosaminoglycan (GAG), collagen, and DNA content. Furthermore, IHC and ICC data demonstrated that both treatments increase the protein expression level of CK19. CONCLUSION: Pretreatment of acellular bioscaffolds by MPLA or LCS can increase the migration rate of cells and also transdifferentiation of hucMSC to epidermal-like cells without growth factors. This strategy suggests a new approach in regenerative medicine.

Use of Acellular Matrices as Scaffolds in Cartilage Regeneration: A Systematic Review.

Significance: Cartilage regeneration remains a significant challenge in the field of regenerative medicine. Acellular matrix (AM)-based cartilage tissue regeneration offers an innovative approach to repairing cartilage defects by providing a scaffold for new tissue growth. Its significance lies in its potential to restore joint function, mitigate pain, and improve the quality of life for patients suffering from cartilage-related injuries and conditions. Recent Advances: Recent advances in AM-based cartilage regeneration have focused on enhancing scaffold properties for improved cell adhesion, proliferation, and differentiation. Moreover, several scaffold techniques such as combining acellular dermal matrix (ADM) and acellular cartilage matrix (ACM) with cartilage tissue, as well as biphasic scaffolding, enjoy rising research activity. Incorporating bioactive factors and advanced manufacturing techniques holds promise for producing more biomimetic scaffolds, advancing efficient cartilage repair and regeneration. Critical Issues: Obstacles in AM-based cartilage regeneration include achieving proper integration with the surrounding tissue and ensuring long-term durability of the regenerated cartilage. Furthermore, issues such as high costs and limited availability of suitable cells for scaffold seeding must be considered. The heterogeneity and limited regenerative capabilities of cartilage need to be addressed for successful clinical translation. Future Directions: Research should focus on exploring advanced biomaterials and developing new techniques, regarding easily reproducible scaffolds, ideally constructed from clinically validated and readily available commercial products. Findings underline the potential of AM-based approaches, especially the rising exploration of tissue-derived ADM and ACM. In future, the primary objective should not only be the regeneration of small cartilage defects but rather focus on fully regenerating a joint or larger cartilage defect.

Engineering a functional ACL reconstruction graft containing a triphasic enthesis-like structure in bone tunnel for the enhancement of graft-to-bone integration.

Background: Anterior cruciate ligament (ACL) rupture is a common sports injury, which causes knee instability and abnormal joint kinematics. The current ACL graft was single-phasic, and not convenient for the formation of enthesis-like tissue in the bone tunnel, resulting in poor integration of graft-to-bone. Methods: A band-shaped acellular tendon (BAT) was prepared as the core component of the ACL reconstruction graft at first, while sleeve-shaped acellular cartilage (SAC) or sleeve-shaped acellular bone (SAB) was fabricated using a vacuum aspiration system (VAS)-based decellularization protocol. The biocompatibility of the three acellular matrixes was evaluated. Furthermore, a collagen-binding peptide (CBP) derived from the A3 domain of von Willebrand factor was respectively fused into the N-terminal of GDF7, TGFß3, or BMP2 to synthesize three recombinant growth factors capable of binding collagen (named C-GDF7, C-TGFß3, or C-BMP2), which were respectively tethered to the BAT, SAC or SAB for improving their inducibilities in stem cell differentiation. An in-vitro experiment was performed to evaluate theirs osteogenic, chondrogenic, and tenogenic inducibilities. Then, C-TGFß3-tethering SAC (C-TGFß3@SAC) and C-BMP2-tethering SAB (C-BMP2@SAB) were sequentially surrounded at the bone tunnel part of C-GDF7-tethering BAT (C-GDF7@BAT), thus a sleeve-shaped acellular graft with a triphasic enthesis-like structure in bone tunnel part (named tissue-engineered graft, TE graft) was engineered. Lastly, a canine ACL reconstruction model was used to evaluate the in-vivo performance of this TE graft in enhancing graft-to-bone integration. Results: The BAT, SAC, and SAB well preserved the structure and components of native tendon, cartilage, and bone, showing good biocompatibility. C-GDF7, C-TGFß3, or C-BMP2 showed a stronger binding ability to BAT, SAC, and SAB. The C-GDF7@BAT, C-TGFß3@SAC, or C-BMP2@SAB was a controlled delivery system for the scaffold-specific release of GDF7, TGFß3, and BMP2, thus showing superior tenogenic, chondrogenic, or osteogenic inducibility, respectively. Using a canine ACL reconstruction model, abundant newly-formed bone and connective collagen fibers could be observed at the integration site between TE graft and bone tunnel at postoperative 16 weeks. Meanwhile, the failure load of the reconstructed ACL by TE graft was significantly higher than that of the autograft. Conclusion: The TE graft could be used to reconstruct ruptured ACL and augment graft-to-bone integration, thus demonstrating high potential for clinical translation in ACL reconstruction. Translational potential of this article: The findings of the study indicated that the TE graft could be a novel graft for ACL reconstruction with the ability to augment graft-to-bone integration, which may provide a foundation for future clinical application.

Tissue engineering strategies for breast reconstruction: a literature review of current advances and future directions.

Background and Objective: Mastectomy is a primary treatment for breast cancer patients, and both autologous and implant-based reconstructive techniques have shown excellent results. In recent years, advancements in bioengineering have led to a proliferation of innovative approaches to breast reconstruction. This article comprehensively explores the promising perspectives offered by bioengineering and tissue engineering in the field of breast reconstruction. Methods: A literature review was conducted between April and June 2023 on PubMed and Google Scholar Databases. All English and French articles related to bioengineering applied to the field of breast reconstruction were included. We used the Evidence-Based Veterinary Medicine Association (EBVM) Toolkit 14 checklist for narrative reviews as a quality assurance measure and the Scale for the Assessment of Narrative Review Articles (SANRA) tool to self-assess our methodology. Key Content and Findings: Over 130 references related to breast bioengineering were included. The analysis revealed four key applications: enhancing the quality of the skin envelope, improving the viability of fat grafting, creating breast shape and volume via bio-printing, and optimizing nipple reconstruction through engineering techniques. The primary identified approaches revolved around establishing structural support and enhancing cellular viability. Structural techniques predominantly involved the implementation of 3D printed, decellularized, or biocompatible material scaffolds. Meanwhile, promoting cellular content trophicity primarily focused on harnessing the regenerative potential of adipose-derived stem cells (ADSCs) and increasing the tissue's survivability and cell trophicity. Conclusions: Tissue and bioengineering hold immense promise in the field of breast reconstruction, offering a diverse array of approaches. By combining existing techniques with novel advancements, they have the potential to significantly enhance the therapeutic options available to plastic and reconstructive surgeons.

Transplantation of beige adipose organoids fabricated using adipose acellular matrix hydrogel improves metabolic dysfunction in high-fat diet-induced obesity and type 2 diabetes mice.

Transplantation of brown adipose tissue (BAT) is a promising approach for treating obesity and metabolic disorders. However, obtaining sufficient amounts of functional BAT or brown adipocytes for transplantation remains a major challenge. In this study, we developed a hydrogel that combining adipose acellular matrix (AAM) and GelMA and HAMA that can be adjusted for stiffness by modulating the duration of light-crosslinking. We used human white adipose tissue-derived microvascular fragments to create beige adipose organoids (BAO) that were encapsulated in either a soft or stiff AAM hydrogel. We found that BAOs cultivated in AAM hydrogels with high stiffness demonstrated increased metabolic activity and upregulation of thermogenesis-related genes. When transplanted into obese and type 2 diabetes mice, the HFD + BAO group showed sustained improvements in metabolic rate, resulting in significant weight loss and decreased blood glucose levels. Furthermore, the mice showed a marked reduction in nonalcoholic liver steatosis, indicating improved liver function. In contrast, transplantation of 2D-cultured beige adipocytes failed to produce these beneficial effects. Our findings demonstrate the feasibility of fabricating beige adipose organoids in vitro and administering them by injection, which may represent a promising therapeutic approach for obesity and diabetes.

Preparation and characterization of a novel composite acellular matrix/hyaluronic acid thermosensitive hydrogel for interstitial cystitis/bladder pain syndrome.

Bladder mucosa damage that causes harm to the interstitium is a recognized pathogenesis of interstitial cystitis/bladder pain syndrome (IC/BPS). The intravesical instillation of drugs is an important second-line therapy, but it is often necessary to use drugs repeatedly in the clinic because of their short residence time in the bladder cavity, which alters the therapeutic effect. To overcome this drawback, this study developed a novel composite acellular matrix/hyaluronic acid (HA) thermosensitive hydrogel (HA-Gel) using rabbit small intestinal submucosa extracellular matrix (ECM) as the thermosensitive material and HA as the drug component and examined its composition, microstructure, thermodynamic properties, temperature sensitivity, rheological properties, biocompatibility, drug release, hydrogel residue, and bacteriostatic properties. The study showed HA-Gel was liquid at temperatures of 15-37.5°C and solid at 37.5-50°C, its swelling rate decreased with increasing temperature, and its lower critical solution temperature occurred at approximately 37.5°C. This property made the hydrogel liquid at room temperature convenient for intravesical perfusion and turned into a solid about 1 min after entering the body and rising to body temperature to increase its residence time. Subsequent experiments also proved that the gel residue time of HA-Gel in vivo and the drug release time of HA in vivo could reach more than 5 days, which was significantly higher than that of HA alone, and it had good biocompatibility and antibacterial properties. Therefore, this hydrogel possesses the proper characteristics to possibly make it an ideal dosage form for IC/BPS intravesical instillation therapy.

Autologous Endothelial Progenitor Cells and Bioactive Factors Improve Bladder Regeneration.

Insufficient vascularization is still a challenge that impedes bladder tissue engineering and results in unsatisfied smooth muscle regeneration. Since bladder regeneration is a complex articulated process, the aim of this study is to investigate whether combining multiple pathways by exploiting a combination of biomaterials, cells, and bioactive factors, contributes to the improvements of smooth muscle regeneration and vascularization in tissue-engineered bladder. Autologous endothelial progenitor cells (EPCs) and bladder smooth muscle cells (BSMCs) are cultured and incorporated into our previously prepared porcine bladder acellular matrix (BAM) for bladder augmentation in rabbits. Simultaneously, exogenous vascular endothelial growth factor (VEGF) and platelet-derived growth factor BB (PDGF-BB) mixed with Matrigel were injected around the implanted cells-BAM complex. In the results, compared with control rabbits received bladder augmentation with porcine BAM seeded with BSMCs, the experimental animals showed significantly improved smooth muscle regeneration and vascularization, along with more excellent functional recovery of tissue-engineered bladder, due to the additional combination of autologous EPCs and bioactive factors, including VEGF and PDGF-BB. Furthermore, cell tracking suggested that the seeded EPCs could be directly involved in neovascularization. Therefore, it may be an effective method to combine multiple pathways for tissue-engineering urinary bladder.

Perfusion preparation of the rat bladder decellularized scaffold.

Introduction: Bladder reconstruction is a huge challenge in the field of urology. In recent years, perfusion methods have brought promising results in the field of tissue engineering. We prepared bladder decellularized scaffolds by improved perfusion, which may be suitable for bladder reconstruction. Methods: We prepared decellularized scaffolds of rat bladder by perfusion of SDS (0.5% sodium dodecyl sulfate), SDS-SDC (0.5% sodium dodecyl sulfate +0.5% sodium deoxycholate). Histological characteristics of bladder decellularized scaffolds were assessed by Hematoxylin and eosin, Masson, and DAPI staining. Moreover, we also prepared a murine bladder transplantation model to evaluate the regenerative potential of scaffolds. Results: Hematoxylin and eosin, Masson, and DAPI staining indicated almost no cellular component residues in the SDS-SDC group. Histological analysis (hematoxylin and eosin staining, Masson staining), CD31 and F4/80 staining analysis, one month after implantation, revealed that the decellularized scaffolds had regenerative characteristics, and the SDS-SDC scaffold had better regenerative properties than the SDS scaffold. Conclusions: We successfully prepared the decellularized scaffold for the rat bladder by perfusion. Our results showed that the SDS-SDC scaffold had better decellularization efficiency and reconstruction ability than the SDS scaffold, which provides a new perspective on bladder reconstruction materials.

Polycaprolactone/graphene oxide/acellular matrix nanofibrous scaffolds with antioxidant and promyelinating features for the treatment of peripheral demyelinating diseases.

Peripheral demyelinating diseases entail damage to axons and Schwann cells in the peripheral nervous system. Because of poor prognosis and lack of a cure, this group of diseases has a global impact. The primary underlying cause of these diseases involves the inability of Schwann cells to remyelinate the damaged insulating myelin around axons, resulting in neuronal death over time. In the past decade, extensive research has been directed in the direction of Schwann cells focusing on their physiological and neuroprotective effects on the neurons in the peripheral nervous system. One cause of dysregulation in the remyelinating function of Schwann cells has been associated with oxidative stress. Tissue-engineered biodegradable scaffolds that can stimulate remyelination response in Schwann cells have been proposed as a potential treatment strategy for peripheral demyelinating diseases. However, strategies developed to date primarily focussed on either remyelination or oxidative stress in isolation. Here, we have developed a multifunctional nanofibrous scaffold with material and biochemical cues to tackle both remyelination and oxidative stress in one matrix. We developed a nanofibrous scaffold using polycaprolactone (PCL) as a foundation loaded with antioxidant graphene oxide (GO) and coated this bioscaffold with Schwann cell acellular matrix. In vitro studies revealed both antioxidant and remyelination properties of the developed bioscaffold. Based on the results, the developed multifunctional bioscaffold approach can be a promising biomaterial approach for treating demyelinating diseases.

Porous gelatin microspheres implanted with adipose mesenchymal stromal cells promote angiogenesis via protein kinase B/endothelial nitric oxide synthase signaling pathway in bladder reconstruction.

BACKGROUND AIMS: Cell failure and angiogenesis are the key to bladder wall regeneration. Three-dimensional (3D) culture using porous gelatin microspheres (GMs) as a vehicle promotes stem cell proliferation and improves the paracrine capacity of cells. This study aimed to evaluate the therapeutic potential of GMs constructed from adipose-derived mesenchymal stromal cells (ADSCs) (ADSC-GMs) combined with bladder acellular matrix (BAM) in tissue-engineered bladders. METHODS: Isolation of ADSCs, flow cytometry, scanning electron microscopy and cell counting kit-8, ß-galactosidase and enzyme-linked immunosorbent assays were performed in vitro to compare two-dimensional (2D) and 3D cultures. In the in vivo study, male Sprague-Dawley rats were randomly divided into three groups: the BAM replacement alone (BAM) group, ADSCs grown on BAM in replacement (ADSC) group and ADSC-GMs combined with BAM followed by replacement (ADSC-GM) group. Bladder function assessed by urodynamics after 12 weeks of bladder replacement, and the rats were sacrificed at 4 and 12 weeks for further experiments. RESULTS: The in vitro results showed that GM culture promoted ADSC proliferation, inhibited apoptosis and delayed senescence compared with those in the 2D culture. In addition, ADSC-GMs increased the secretion of the angiogenic factors vascular endothelial growth factor, platelet-derived growth factor-BB, and basal fibroblast growth factor. In vivo experiments revealed that ADSC-GMs adhered to the BAM for longer than ADSCs. Moreover, ADSC-GMs significantly promoted the regeneration of bladder vessels and smooth muscle, thereby facilitating the recovery of bladder function. The expression of phosphorylated protein kinase B (AKT) and phosphorylated endothelial nitric oxide synthase (eNOS) was significantly greater in the ADSC-GMs group compared with the BAM and ADSCs groups. CONCLUSIONS: ADSC-GMs increased retention of ADSCs on the BAM, thereby promoting the regeneration and functional recovery of the bladder tissue. ADSC-GMs promoted angiogenesis by activating the AKT/eNOS pathway.

A novel allogeneic acellular matrix scaffold for porcine cartilage regeneration.

BACKGROUND: Cartilage defects are common sports injuries without significant treatment. Articular cartilage with inferior regenerative potential resulted in the poor formation of hyaline cartilage in defects. Acellular matrix scaffolds provide a microenvironment and biochemical properties similar to those of native tissues and are widely used for tissue regeneration. Therefore, we aimed to design a novel acellular cartilage matrix scaffold (ACS) for cartilage regeneration and hyaline-like cartilage formation. METHODS: Four types of cartilage injury models, including full-thickness cartilage defects (6.5 and 8.5 mm in diameter and 2.5 mm in depth) and osteochondral defects (6.5 and 8.5 mm in diameter and 5 mm in depth), were constructed in the trochlear groove of the right femurs of pigs (n = 32, female, 25-40 kg). The pigs were divided into 8 groups (4 in each group) based on post-surgery treatment differences. was assessed by macroscopic appearance, magnetic resonance imaging (MRI), micro-computed tomography (micro-CT), and histologic and immunohistochemistry tests. RESULTS: At 6 months, the ACS-implanted group exhibited better defect filling and a greater number of chondrocyte-like cells in the defect area than the blank groups. MRI and micro-CT imaging evaluations revealed that ACS implantation was an effective treatment for cartilage regeneration. The immunohistochemistry results suggested that more hyaline-like cartilage was generated in the defects of the ACS-implanted group. CONCLUSIONS: ACS implantation promoted cartilage repair in full-thickness cartilage defects and osteochondral defects with increased hyaline-like cartilage formation at the 6-month follow-up.

Comparative proteomic analysis of regenerative acellular matrices: The effects of tissue source and processing method.

Acellular tissue matrices are used in regenerative medicine from weak tissue re-enforcement to cosmetic augmentation. However, proteomic signatures leading to different clinical outcomes among matrices are not well understood. In an attempt to investigate the effects of tissue source and processing method, we examined by liquid chromatography tandem mass spectrometry (LC-MS/MS) the proteomic profiles of 12 regulatory agency-approved acellular matrices (AlloMax, AlloDerm, CollaMend, Heal-All, JayyaLife, ReGen, Renov, Strattice, SurgiMend, Surgisis, UniTrump and Vidasis). The compositions of acellular matrices varied greatly with the number of identified proteins ranging from 7 to 106. The content of individual proteins was between 0.0001% and 95.8% according to their abundances measured by the M/Z signal intensities. Most acellular matrices still contained numerous cellular proteins. AlloMax, AlloDerm, ReGen, Strattice, SurgiMend and Surgisis retained necessary structural and functional proteins to form the extracellular protein-protein interaction networks for cell adhesion, proliferation and tissue regeneration, whereas CollaMend, Heal-All, JayyaLife, Renov, UniTrump and Vidasis had only retained certain structural collagens. Principal component analysis showed that proteomic variations among acellular matrices were largely attributed to tissue source and processing method. Differences in proteomic profiles among acellular matrices offers insights into molecular interpretation for different clinical outcomes, and can serve as useful references for rational design of regenerative bio-scaffolds.

Otologic use of porcine small intestinal submucosal graft (biodesign): A MAUDE database review.

OBJECTIVE: To review and summarize reported adverse events related to the use of porcine small intestine submucosal grafts (Biodesign™) in otologic procedures. STUDY DESIGN: Retrospective cross-sectional analysis. SETTING: Food and Drug Administration's Manufacturer and User Facility Device Experience (MAUDE) database. MATERIAL AND METHODS: The MAUDE database was queried for all medical device reports (MDR) related to otologic use of Biodesign™ (Cook Medical, Bloomington, IN) from January 2016 to November 2022. Adverse events (AEs) were identified by reviewing all reports with the basic search term "Biodesign" and "Biodesign, Otologic". Reports were individually reviewed and categorized with special attention to AEs. RESULTS: A total of 500 reports were reviewed. Since FDA approval of Biodesign™ in 2016, there have been 5 adverse events reported for use of Biodesign™ during otologic surgery (tympanoplasty, n = 3; stapes surgery, n = 2). All reported events described patient injury, and all cases required at least one revision surgery. Four cases described significant foreign body inflammatory reactions. Complications included hearing loss (n = 3), severe otalgia (n = 2), persistent perforation (n = 2), vertigo (n = 2), and facial paralysis (n = 1). CONCLUSION: The use of porcine small intestinal submucosal graft has been thought to be a safe and effective option for otologic surgery, with the advantage of availability without graft harvest in minimally invasive endoscopic surgery. However, foreign body or granulomatous reactions have been documented and should be considered prior to its use in otologic surgery.

Reconstruction of delayed distal biceps ruptures with a dermal matrix.

OBJECTIVES: Distal biceps tear is uncommon, with well-recognized risk factors and typical clinical presentation. Delays in surgical treatment lead to several challenges, such as tendon retraction and tendon degeneration. We present a surgical technique using a sterilized acellular dermal matrix, which provides a solution for a challenging pathology. MATERIAL AND METHODS: We present a detailed surgical technique of distal biceps reconstruction with acellular dermal matrix, performed in 4 patients, with an average time to diagnosis of 36 days (range, 28-45 days). Demographics, clinical data, range of motion and subjective satisfaction were collected. RESULTS: At a mean follow-up of 18 months, all 4 patients showed full range of motion and strength, complete recovery and previous work resumed without pain. No complications appeared during this time. CONCLUSIONS: Delayed distal biceps tear reconstruction by acellular dermal matrix showed promising results. Meticulous surgical technique using this matrix provided excellent reconstruction, with very solid anatomical repair and exceptionally good fixation, good clinical outcome and satisfied patients. LEVEL OF EVIDENCE: IV.

Development and In Vivo Assessment of an Injectable Cross-Linked Cartilage Acellular Matrix-PEG Hydrogel Scaffold Derived from Porcine Cartilage for Tissue Engineering.

The cartilage acellular matrix (CAM) derived from porcine cartilage, which does not induce significant inflammation and provides an environment conducive for cell growth and differentiation, is a promising biomaterial candidate for scaffold fabrication. However, the CAM has a short period in vivo, and the in vivo maintenance is not controlled. Therefore, this study is aimed at developing an injectable hydrogel scaffold using a CAM. The CAM is cross-linked with a biocompatible polyethylene glycol (PEG) cross-linker to replace typically used glutaraldehyde (GA) cross-linker. The cross-linking degree of cross-linked CAM by PEG cross-linker (Cx-CAM-PEG) according to the ratios of the CAM and PEG cross-linker is confirmed by contact angle and heat capacities measured by differential scanning calorimetry. The injectable Cx-CAM-PEG suspension exhibits controllable rheological properties and injectability. Additionally, injectable Cx-CAM-PEG suspensions with no free aldehyde group are formed in the in vivo hydrogel scaffold almost simultaneously with injection. In vivo maintenance of Cx-CAM-PEG is realized by the cross-linking ratio. The in vivo formed Cx-CAM-PEG hydrogel scaffold exhibits certain host-cell infiltration and negligible inflammation within and near the transplanted Cx-CAM-PEG hydrogel scaffold. These results suggest that injectable Cx-CAM-PEG suspensions, which are safe and biocompatible in vivo, represent potential candidates for (pre-)clinical scaffolds.

Study on the preparation and properties of acellular matrix from the skin of silver carp (Hypophthalmichthys molitrix).

Acellular matrices are mainly composed of mammalian tissues, and aquatic tissues with lower biological risks and less religious restrictions are considered alternatives to mammalian tissues. The acellular fish skin matrix (AFSM) has been commercially available. Silver carp has the advantages of farmability, high yield and low price, but there are few studies on the silver carp acellular fish skin matrix (SC-AFSM). In this study, an acellular matrix with low DNA and endotoxin was prepared from the skin of silver carp. After treatment with trypsin/sodium dodecyl sulfate and Triton X-100 solutions, the DNA content in SC-AFSM reached 11.03 ± 0.85 ng/mg, and the endotoxin removal rate was 96.8%. The porosity of SC-AFSM was 79.64% ± 0.17%, which is favorable for cell infiltration and proliferation. The relative cell proliferation rate of SC-AFSM extract was 117.79% ± 15.26%. The wound healing experiment showed that SC-AFSM had no adverse acute pro-inflammatory response, which had a similar effect as commercial products in promoting tissue repair. Therefore, SC-AFSM has great application potential in biomaterials.

The study of the whole bladder acellular matrix prepared by the perfusion decellularization system combined with the adipose-derived stem cells to construct the tissue engineering bladder / 中华泌尿外科杂志

Objective:To prepare the whole bladder acellular matrix (BAM) using the self-designed perfusion decellularization system, and evaluate the feasibility of constructing the tissue engineering bladder with the adipose-derived stem cells (ADSCs).Methods:This study was conducted from October 2020 to April 2021. The self-designed perfusion decellularization system was used, and four different decellularization protocols (group A, group B, group C and group D) were formulated, according to the flow direction of the perfusate and the action time of different decellularization solutions. Among them, the urethral orifice of the bladder tissue was used as the outflow tract of the perfusion fluid in groups A and B. The top of the bladder was cut off and used as the outflow tract of the perfusion fluid in groups C and D. In groups A and C, 1% Triton X-100 was treated for 6 h, and 1% sodium dodecyl sulfate (SDS) was treated for 2 h. In groups B and D, 1% Triton X-100 was treated for 7 h, and 1% sodium dodecyl sulfate (SDS) was treated for 1 h. In addition, the tissue in the normal bladder group was directly obtained from the natural bladder tissue, which did not require perfusion, cryopreservation and thawing. The fast and efficient decellularization protocol was screened out through HE, DAPI, Masson trichrome and Alcian Blue staining and quantitative analyses to prepare the whole bladder scaffold. The prepared BAM was used as the scaffold material, and the ADSCs were used as the seeding cells to construct the tissue engineering bladder. HE and DAPI staining were used to observe the distribution of ADSCs on the BAM.Results:HE and DAPI staining showed that there was no obvious nuclear residue in the group C. Masson trichrome and Alcian Blue staining showed that the collagen structure and glycosaminoglycan were well preserved in the group C. There was no significant difference in bladder wall thickness between the group C and the normal bladder group [(975.44±158.62)μm vs.(1 064.49±168.52)μm, P > 0.05]. The DNA content in the group C [(43.59 ±4.59) ng/mg] was lower than that in the normal bladder group, group A, group B and group D [(532.50±26.69), (135.17±6.99), (182.49±13.69) and(84.00±4.38)ng/mg], and the difference was statistically significant ( P<0.05). The collagen content [(10.98 ± 0.29)μg/mg] and glycosaminoglycan content [(2.30±0.18)μg/mg] in group C were not significantly different with those in the normal bladder group [(11.69±0.49) and (2.36±0.09)μg/mg, P>0.05]. Scanning electron microscopy showed that a large number of pore structures could be observed on the surface of the prepared BAM in groups A-D and were facilitated to cell adhesion. The isolated and cultured ADSCs were identified by flow cytometry to confirm the positive expression of CD90 and CD29, and the negative expression of CD45 and CD106. Live/dead staining and CCK-8 detection confirmed that the prepared BAM in the group C had no cytotoxicity. HE and DAPI staining showed that a large number of ADSCs were distributed on the surface and inside of the tissue engineering bladder. Conclusions:The whole bladder shape BAM prepared by the self-designed perfusion decellularization system could be used as the scaffold material for bladder tissue engineering, and the constructed tissue engineering bladder could be used for bladder repair and reconstruction.

Fabrication of biphasic cartilage-bone integrated scaffolds based on tissue-specific photo-crosslinkable acellular matrix hydrogels.

The fabrication of biphasic cartilage-bone integrated scaffolds is an attractive alternative for osteochondral repair but has proven to be extremely challenging. Existing three-dimensional (3D) scaffolds are insufficient to accurately biomimic the biphasic cartilage-bone integrated microenvironment. Currently, photo-crosslinkable hydrogels based on tissue-specific decellularized extracellular matrix (dECM) have been considered as an important technique to fabricate biomimetic scaffolds, but so far there has been no breakthrough in the photo-crosslinkable hydrogel scaffolds with biphasic cartilage-bone biomimetic microenvironment. Here, we report a novel strategy for the preparation of biomimetic cartilage-bone integrated scaffolds based on photo-crosslinkable cartilage/bone-derived dECM hydrogels, which are able to reconstruct biphasic cartilage-bone biomimetic microenvironment. The biphasic cartilage-bone integrated scaffolds provided a 3D microenvironment for osteochondral regeneration. The cartilage biomimetic scaffolds, consisting of cartilage-derived dECM hydrogels, efficiently regulated chondrogenesis of bone marrow mesenchymal stem cells (BMSCs). The bone biomimetic scaffolds, composed of cartilage/bone-derived dECM hydrogels, first regulated chondrogenesis of BMSCs, followed by endochondral ossification over time. Taken together, the biphasic cartilage-bone integrated tissue could be successfully reconstructed by subcutaneous culture based on cartilage-bone bilayered structural design. Furthermore, the biphasic cartilage-bone biomimetic scaffolds (cell-free) achieved satisfactory cartilage-bone integrated regeneration in the osteochondral defects of rabbits' knee joints.

Are patients most satisfied with a synthetic or a biological mesh in dual-plane immediate breast reconstruction after 5 years? A randomized controlled trial comparing the two meshes in the same patient.

Biological or synthetic meshes are commonly used in implant-based immediate breast reconstruction (IBR). The aim of this study was to compare patient-reported outcome measurements (PROMs) after IBR with a synthetic mesh and a biological mesh, in a single-blinded randomized controlled trial, using the compared materials in the same patient, thereby eliminating patient-related confounders. Twenty-four patients were recruited, and all patients had a prophylactic bilateral mastectomy and a dual-plane reconstruction using anatomical breast implants. The patients' two breasts were randomized preoperatively to a biological or a synthetic mesh, using a simple approach with a parallel design. PROMs were measured with BREAST-Q. Twenty-one patients answered (88%). Most participants were equally satisfied/dissatisfied with the synthetic and the biological mesh sides regarding size of bra, softness, feel to touch, natural part of body, appearance compared with preoperatively, and palpable wrinkles, and about half of the patients regarding shape of bra, natural appearance, and visible wrinkles. The frequency of capsular contracture rate was zero in both groups at 5 years. One mesh type was not clearly superior to the other regarding PROMs, but biological and synthetic meshes seem to give rise to different types of reconstructed breasts, and more studies are needed regarding whether knowledge about the effects of different meshes can be used to tailor breast reconstructions to individual patients' wishes. The rate of complications and corrections in the biological mesh breasts was higher, and this must be considered when the type of mesh is chosen. Trial registration number: ClinicalTrials.Gov identifier NCT02985073.