Effect of Microsphere Concentration on Catechin Release from Microneedle Arrays.

In this work, microspheres were developed by cross-linking glutaraldehyde in an aqueous gelatin solution with a surfactant and solvent. A poly(vinyl alcohol) (PVA) solution was produced and combined with catechin-loaded microspheres. Different microsphere concentrations (0%, 5%, 10%, and 15%) were applied to the PVA microneedles. The moisture content, particle size, swelling, and drug release percentage of microneedles were studied using various microsphere concentrations. Fourier transform infrared and scanning electron microscopy (SEM) investigations validated the structure of gelatin microspheres as well as their decoration in microneedles. The SEM scans revealed that spherical microspheres with a wrinkled and folded morphology were created, with no physical holes visible on the surface. The gelatin microspheres generated had a mean particle size of 20-30 µm. Ex vivo release analysis indicated that microneedles containing 10% microspheres released the most catechin, with 42.9% at 12 h and 84.4% at 24 h.

Gelatin Microspheres Based on H8-Loaded Macrophage Membrane Vesicles to Promote Wound Healing in Diabetic Mice.

Diabetic wound healing remains a worldwide challenge for both clinicians and researchers. The high expression of matrix metalloproteinase 9 (MMP9) and a high inflammatory response are indicative of poor diabetic wound healing. H8, a curcumin analogue, is able to treat diabetes and is anti-inflammatory, and our pretest showed that it has the potential to treat diabetic wound healing. However, H8 is highly expressed in organs such as the liver and kidney, resulting in its unfocused use in diabetic wound targeting. (These data were not published, see Table S1 in the Supporting Information.) Accordingly, it is important to pursue effective carrier vehicles to facilitate the therapeutic uses of H8. The use of H8 delivered by macrophage membrane-derived nanovesicles provides a potential strategy for repairing diabetic wounds with improved drug efficacy and fast healing. In this study, we fabricated an injectable gelatin microsphere (GM) with sustained MMP9-responsive H8 macrophage membrane-derived nanovesicles (H8NVs) with a targeted release to promote angiogenesis that also reduces oxidative stress damage and inflammation, promoting diabetic wound healing. Gelatin microspheres loaded with H8NV (GMH8NV) stimulated by MMP9 can significantly facilitate the migration of NIH-3T3 cells and facilitate the development of tubular structures by HUVEC in vitro. In addition, our results demonstrated that GMH8NV stimulated by MMP9 protected cells from oxidative damage and polarized macrophages to the M2 phenotype, leading to an inflammation inhibition. By stimulating angiogenesis and collagen deposition, inhibiting inflammation, and reducing MMP9 expression, GMH8NV accelerated wound healing. This study showed that GMH8NVs were targeted to release H8NV after MMP9 stimulation, suggesting promising potential in achieving satisfactory healing in diabetic treatment.

Multilevel chitosan-gelatin particles loaded with P4HA1 siRNA suppress glioma development.

It has been reported that prolyl 4-hydroxylase subunit alpha 1 (P4HA1) promoted tumor growth and metastasis of glioma; thus, targeting P4HA1 may be a promising therapeutic strategy against glioma. In consideration of the instability of siRNA in vivo, the chitosan-gelatin microspheres loaded with P4HA1 siRNA (P4HA1 siRNA@CGM) were employed. Firstly, the gel electrophoresis and hemolytic test were performed to assess the stability and blood compatibility of P4HA1 siRNA@CGM. Then, methyl thiazolyl tetrazolium (MTT), cell colony formation, Transwell assay, wound healing assay, gliosphere formation, tube formation, and Western blot were performed to assess the effects of P4HA1 siRNA@CGM on the biological functions of glioma. Finally, 125I-labeled P4HA1 siRNA@CGM was injected into the xenograft mice, radionuclide imaging was recorded, Ki67 and terminal deoxynucleoitidyl transferase-mediated nick end labeling (TUNEL) staining was performed to assess the effects of P4HA1 siRNA@CGM on tumor growth and apoptosis of glioma in vivo. The results showed that P4HA1 siRNA and P4HA1 siRNA@CGM not only markedly inhibited the proliferation, metastasis, gliosphere formation, and the protein levels of interstitial markers (N-cadherin and vimentin) and the transcription factors of epithelial-mesenchymal transition (EMT) (Snail, Slug, and Twist1) in glioma cells, but also inhibited the tube formation in human brain microvascular endothelial cells (HBMECs), and P4HA1 siRNA@CGM exhibited the better inhibitory effects than P4HA1 siRNA. Above results suggested the feasibility of P4HA1 siRNA@CGM in the clinical treatment of glioma.

Transplantation of Gelatin Microspheres Loaded with Wharton's Jelly Derived Mesenchymal Stem Cells Facilitates Cartilage Repair in Mice.

BACKGROUND: Knee osteoarthritis (KOA) is a prevalent chronic joint disease caused by various factors. Mesenchymal stem cells (MSCs) therapy is an increasingly promising therapeutic option for osteoarthritis. However, the chronic inflammation of knee joint can severely impede the therapeutic effects of transplanted cells. Gelatin microspheres (GMs) are degradable biomaterial that have various porosities for cell adhesion and cell-cell interaction. Excellent elasticity and deformability of GMs make it an excellent injectable vehicle for cell delivery. METHODS: We created Wharton's jelly derived mesenchymal stem cells (WJMSCs)-GMs complexes and assessed the effects of GMs on cell activity, proliferation and chondrogenesis. Then, WJMSCs loaded in GMs were transplanted in the joint of osteoarthritis mice. After four weeks, joint tissue was collected for histological analysis. Overexpressing-luciferase WJMSCs were performed to explore cell retention in mice. RESULTS: In vitro experiments demonstrated that WJMSCs loaded with GMs maintained cell viability and proliferative potential. Moreover, GMs enhanced the chondrogenesis differentiation of WJMSCs while alleviated cell hypertrophy. In KOA mice model, transplantation of WJMSCs-GMs complexes promoted cartilage regeneration and cartilage matrix formation, contributing to the treatment of KOA. Compared with other groups, in WJMSCs+GMs group, there were fewer cartilage defects and with a more integrated tibia structure. Tracking results of stable-overexpressing luciferase WJMSCs demonstrated that GMs significantly extended the retention time of WJMSCs in knee joint cavity. CONCLUSION: Our results indicated that GMs facilitate WJMSCs mediated knee osteoarthritis healing in mice by promoting cartilage regeneration and prolonging cell retention. It might potentially provide an optimal strategy for the biomaterial-stem cell based therapy for knee osteoarthritis.

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.

[Application of gelatin microspheres in bone tissue engineering].

Gelatin microspheres were discussed as a scaffold material for bone tissue engineering, with the advantages of its porosity, biodegradability, biocompatibility, and biosafety highlighted. This review discusses how bone regeneration is aided by the three fundamental components of bone tissue engineering-seed cells, bioactive substances, and scaffold materials-and how gelatin microspheres can be employed for in vitro seed cell cultivation to ensure efficient expansion. This review also points out that gelatin microspheres are advantageous as drug delivery systems because of their multifunctional nature, which slows drug release and improves overall effectiveness. Although gelatin microspheres are useful for bone tissue creation, the scaffolds that take into account their porous structure and mechanical characteristics might be difficult to be created. This review then discusses typical techniques for creating gelatin microspheres, their recent application in bone tissue engineering, as well as possible future research directions.

Effects of Adding Chitosan on Drug Entrapment Efficiency and Release Duration for Paclitaxel-Loaded Hydroxyapatite-Gelatin Composite Microspheres.

Hydroxyapatite-gelatin microspheres with cone-like pores were synthesized via the wet-chemical method using ammonium dihydrogen phosphate ((NH4)H2PO4) and calcium nitrate (Ca(NO3)2·4H2O) as a source of calcium and phosphate ions with the addition of gelatin, which proved to be more osteoconductive than commercial products, such as fibrin glue and Osteoset® Bone Graft Substitute. Following the method of the previous study for loading paclitaxel (PTX), a drug entrapment efficiency of around 58% was achieved, which is much lower than that of the doxorubicin (DOX)-loaded one. Since PTX is hydrophobic while DOX is hydrophilic, the order of chitosan processing and addition of the solvent were tuned in this study, finally leading to an increase in drug entrapment efficiency of 94%. Additionally, the release duration of PTX exceeded six months. The MTT assay indicated that the effect of drug release on the suppression of cancer cells reached more than 40% after one week, thereby showcasing PTX's capacity to carry out its medicinal functions without being affected by the loading procedures.

Delivery of FGF10 by implantable porous gelatin microspheres for treatment of spinal cord injury.

Porous gelatin microspheres (GMSs) were constructed to enhance the neuroprotective effects of fibroblast growth factor 10 (FGF10) against spinal cord injury (SCI). The GMSs were prepared using a water­in­oil emulsion, followed by cross­linking, washing and drying. The blank GMSs had a mean particle size of 35 µm, with a coarse and porous surface. FGF10 was encapsulated within bulk GMSs via diffusion. To evaluate the effects of the FGF10­GMSs, locomotion tests were performed as a measure of the functional recovery of rats. Hematoxylin and eosin and Nissl staining were used to quantify tissue injury, and Evans blue staining was used to evaluate blood­spinal cord barrier restoration. Western blotting and TUNEL assays were employed to assess apoptotic activity. Immunohistochemical staining of neurofilament antibodies (NF200) was used to evaluate axonal rehabilitation. Compared with the groups intravenously administered FGF10 alone, disruption of the blood­spinal cord barrier and tissue injury were attenuated in the FGF10­GMS group; this group also showed less neuronal apoptosis, as well as enhanced neuronal and axonal rehabilitation. Implantable porous GMSs could serve as carriers for FGF10 in the treatment of SCI.

The Transfer of the Hepatocyte Growth Factor Gene by Macrophages Ameliorates the Progression of Peritoneal Fibrosis in Mice.

Growing evidence indicates that hepatocyte growth factor (HGF) possesses potent antifibrotic activity. Furthermore, macrophages migrate to inflamed sites and have been linked to the progression of fibrosis. In this study, we utilized macrophages as vehicles to express and deliver the HGF gene and investigated whether macrophages carrying the HGF expression vector (HGF-M) could suppress peritoneal fibrosis development in mice. We obtained macrophages from the peritoneal cavity of mice stimulated with 3% thioglycollate and used cationized gelatin microspheres (CGMs) to produce HGF expression vector-gelatin complexes. Macrophages phagocytosed these CGMs, and gene transfer into macrophages was confirmed in vitro. Peritoneal fibrosis was induced by intraperitoneal injection of chlorhexidine gluconate (CG) for three weeks; seven days after the first CG injection, HGF-M was administered intravenously. Transplantation of HGF-M significantly suppressed submesothelial thickening and reduced type III collagen expression. Moreover, in the HGF-M-treated group, the number of α-smooth muscle actin- and TGF-ß-positive cells were significantly lower in the peritoneum, and ultrafiltration was preserved. Our results indicated that the transplantation of HGF-M prevented the progression of peritoneal fibrosis and indicated that this novel gene therapy using macrophages may have potential for treating peritoneal fibrosis.

Comparison of polyvinyl alcohol particles and tris-acryl gelatin microspheres embolic agents used in uterine artery embolization: A systematic review and meta-analysis.

Objective: To identify the preferred agent by comparing the therapeutic efficacy, degree of infarction, and side effects of polyvinyl alcohol particles (PVA) and tris-acryl gelatin embolization (TAGM) agents in uterine artery embolization. Materials and Methods: We included available articles comparing PVA with TAGM embolization agents in the management of fibroids. The primary outcomes included the decrease in uterine volume (%), decrease in dominant tumor volume (%), fibroid infarction rate, complete infarction fibroid, complications, pain score after 24 h, procedure time (minutes), duration of hospital stay, fluoroscopy time (minutes), and the change in symptom severity score. Results: Eight articles that met our inclusion criteria were included in this study. Our analysis yielded an overall superiority of PVA compared to TAGM regarding complete fibroid infarction rate at the first 24 h. However, TAGM was better than PVA concerning <90% infarction rate outcome. While both embolization techniques showed similar effects regarding the change in symptom severity score, the percentage of decrease in uterine volume, percentage of decrease of dominant tumor volume, 90-99% infarction rate, complete infarction rate when assessed after the first 24 h, pain score after the first 24 h, procedure time, fluoroscopy time, minor, and major complications. Conclusion: Both PVA and TAGM embolization agents are effective and safe modalities in treating patients with fibroids, with no significant variation of both agents in most outcomes.

3D Gelatin Microsphere Scaffolds Promote Functional Recovery after Spinal Cord Hemisection in Rats.

Spinal cord injury (SCI) damages signal connections and conductions, with the result that neuronal circuits are disrupted leading to neural dysfunctions. Such injuries represent a serious and relatively common central nervous system condition and current treatments have limited success in the reconstruction of nerve connections in injured areas, especially where sizeable gaps are present. Biomaterial scaffolds have become an effective alternative to nerve transplantation in filling these gaps and provide the foundation for simulating the 3D structure of solid organs. However, there remain some limitations with the application of 3D bioprinting for preparation of biomaterial scaffolds. Here, the approach in constructing and testing mini-tissue building blocks and self-assembly, solid 3D gelatin microsphere (GM) scaffolds with multiple voids as based on the convenient preparation of gelatin microspheres by microfluidic devices is described. These 3D GM scaffolds demonstrate suitable biocompatibility, biodegradation, porosity, low preparation costs, and relative ease of production. Moreover, 3D GM scaffolds can effectively bridge injury gaps, establish nerve connections and signal transductions, mitigate inflammatory microenvironments, and reduce glial scar formation. Accordingly, these 3D GM scaffolds can serve as a novel and effective bridging method to promote nerve regeneration and reconstruction and thus recovery of nerve function after SCI.

Gelatin Microspheres Loaded with Wharton's Jelly Mesenchymal Stem Cells Promote Acute Full-Thickness Skin Wound Healing and Regeneration in Mice.

Objective: At present, there is an urgent need to develop a novel and practical therapeutic approach to accelerate the healing of acute wounds. Mesenchymal stem cell (MSC)-based therapy is emerging as a promising therapeutic approach for acute skin wounds. However, there are still challenges in clinical application of this strategy, such as low survivability, low retention time, and less engraftment in skin wounds. Approach: Wharton's jelly mesenchymal stem cells (WJMSCs) were seeded into three-dimensional (3D) gelatin microspheres (GMs) to identify the biocompatibility of GMs. WJMSCs were embedded in GMs and then encapsulated with Pluronic F-127 (PF-127) and sodium ascorbyl phosphate (SAP) combination to transplant onto acute full-thickness skin wound in mice. Histology, immunohistochemistry, and immunofluorescence assay were used to investigate the skin wound healing, dermis regeneration, collagen deposition, cell proliferation, and neovascularization. Results: Three-dimensional GM had strong biocompatibility, compared with two-dimensional adherent culturing, GM loading increased the cell viability and proliferation ability of WJMSCs. WJMSCs+GM+PF-127+SAP transplantation increased skin wound healing rate, dermis regeneration, and type III collagen deposition through improving macrophage polarization, cell proliferation, neovascularization, cell retention, and engraftment at skin wound site. Innovation: The effective 3D encapsulation technology for WJMSCs solved the main problems of cell activity and residence time during MSC transplantation. WJMSCs+GM+PF-127+SAP transplantation will be a new and effective MSC biomaterials-based therapeutic strategy for acute skin traumatic wounds. Conclusion: WJMSCs+GM+PF-127+SAP transplantation facilitated acute full-thickness skin wound healing and regeneration and might be a new and effective therapy for acute skin traumatic wounds.

Application of gelatin microspheres in bone tissue engineering / 生物工程学报

Gelatin microspheres were discussed as a scaffold material for bone tissue engineering, with the advantages of its porosity, biodegradability, biocompatibility, and biosafety highlighted. This review discusses how bone regeneration is aided by the three fundamental components of bone tissue engineering-seed cells, bioactive substances, and scaffold materials-and how gelatin microspheres can be employed for in vitro seed cell cultivation to ensure efficient expansion. This review also points out that gelatin microspheres are advantageous as drug delivery systems because of their multifunctional nature, which slows drug release and improves overall effectiveness. Although gelatin microspheres are useful for bone tissue creation, the scaffolds that take into account their porous structure and mechanical characteristics might be difficult to be created. This review then discusses typical techniques for creating gelatin microspheres, their recent application in bone tissue engineering, as well as possible future research directions.

Calcium phosphate cement with icariin-loaded gelatin microspheres as a local drug delivery system for bone regeneration.

BACKGROUND: Icariin (ICA), a main active ingredient of Herba Epimedium, could promote bone formation, inhibit bone resorption and alleviate inflammatory responses. The aim of this study was to investigate the effect of ICA on the inhibition of bacteria associated with peri-implantitis, and fabricate a calcium phosphate cement (CPC) with ICA-loaded gelatin microspheres (GMs) as a local drug delivery system efficiently promoting bone formation and alleviating inflammation. RESULTS: In this study, ICA exhibited antibacterial activity against P. gingivalis with a MIC value of 1 × 10-4 mol/L. When the concentration of ICA was 0.5 mM, the encapsulation efficiency of GMs reached the maximum value of 76.26 ± 3.97%. GMs with ICA revealed a controlled release profile, 0.5 mM ICA exhibited a higher ICA release profile than the other groups during a 21 d monitoring span. The results of SEM and XRD demonstrated successful fabrication of a calcium phosphate cement with ICA-loaded GMs. ICA released from CPC/GMs (ICA) was slower than ICA released from GMs within 10 days. CPC/GMs (ICA) exhibited antibacterial activity against P. gingivalis, but the antibacterial rate of CPC/GMs (ICA) was only 17.15 ± 6.06%. In addition, CPC/GMs (ICA) promoted the proliferation of BMSCs and significantly stimulated the differentiation and maturation of BMSCs. In vivo, H&E and Masson staining experiments demonstrated that CPC/GMs (ICA) exhibited better capacity for bone regeneration than CPC/GMs and CPC, and the expression of TNF-α and IL-1ß in the tissue around CPC/GMs (ICA) was significantly lower than CPC/GMs and CPC in IHC staining (P < 0.05). CONCLUSION: In this study, ICA exhibited limited antibacterial activity against bacteria associated with peri-implantitis. A composite material of calcium phosphate cement with ICA-loaded gelatin microspheres was developed, which not only promoting osteoinductivity and bone formation, but also alleviating inflammation, demonstrating its potential as a promising bone substitute material for treatment of peri-implantitis.

Effects of Chitosan on Loading and Releasing for Doxorubicin Loaded Porous Hydroxyapatite-Gelatin Composite Microspheres.

Porous hydroxyapatite-gelatin (Hap-Gel) composite microspheres derived by wet chemical methods were used as carriers of doxorubicin (DOX) coupled with chitosan (Chi) for treating cancers. Through X-ray diffraction, specific surface area porosimetry, chemisorption analysis and inductively coupled plasma mass spectrometry, the crystalline phase, composition, morphology, and pore distribution of HAp-Gel microspheres were all characterized. HAp nanosized crystals and Gel polymers form porous microspheres after blending and exhibit a specific surface area of 158.64 m2/g, pore sizes from 3 to 150 nm, and pore volumes of 0.4915 cm3/g. These characteristics are suitable for carriers of DOX. Furthermore, by the addition of chitosan during drug loading, its drug-entrapment efficiency increases from 70% to 99% and the release duration increases from a 100% burst within a day to only 45% over half a year since the pores in the composite microspheres provide a shielding effect throughout the degradation period of the chitosan. According to the MTT tests, cell viability of DOX-Chi/HAp-Gel is 57.64% on day 5, similar to the result treated with DOX only. It is concluded that under the protection of pores in the microspheres, the chitosan abundant of hydroxyls combining HAp-Gel and DOX by forming hydrogen bonds indeed enhances the entrapment efficiency, prolongs the releasing period and maintains DOX's ability to perform medicine functions unaffected after loading.

Injectable temperature-sensitive hydrogel system incorporating deferoxamine-loaded microspheres promotes H-type blood vessel-related bone repair of a critical size femoral defect.

Insufficient vascularization is a major challenge in the repair of critical-sized bone defects. Deferoxamine (DFO) has been reported to play a potential role in promoting the formation of H-type blood vessels, a specialized vascular subtype with coupled angiogenesis and osteogenesis. However, whether DFO promotes the expression of H-type vessels in critical femoral defects with complete periosteal damage remains unknown. Moreover, stable drug loading systems need to be designed owing to the short half-life and high-dose toxic effects of DFO. In this study, we developed an injectable DFO-gelatin microspheres (GMs) hydrogel complex as a stable drug loading system for the treatment of critical femoral defects in rats. Our results showed that sustained release of DFO in critical femoral defects stimulated the generation of functional H-type vessels. The DFO-GMs hydrogel complex effectively promoted proliferation, formation, and migration of human umbilical vein endothelial cells in vitro. In vivo, the application of the DFO-GMs hydrogel complex expanded the distribution range and prolonged the expression time of H-type vessels in the defect area and was positively correlated with the number of osterix+ cells and new bone tissue. Topical application of the HIF-1α inhibitor PX-478 partially blocked the stimulation of H-type vessels by DFO, whereas the osteogenic potential of the latter was also weakened. Our results extended the local application of DFO and provided a theoretical basis for targeting H-type vessels to treat large femoral defects. STATEMENT OF SIGNIFICANCE: Abundant functional blood vessels are essential for bone repair. The H-type blood vessel is a functional subtype with angiogenesis and osteogenesis coupling potential. A drug loading system with long-term controlled release was first used to investigate the formation of H-type blood vessels in critical femoral defects and promotion of bone repair. Our results showed that the application of DFO-GMs hydrogel complex expanded the distribution range and expression time of H-type vessels, and was positively correlated with the number of osteoblasts and volume of new bone tissue. These results expanded the local application approach of DFO and provide a theoretical basis for targeting H-type vessels to treat large femoral defects.

Adaptive Gelatin Microspheres Enhanced Stem Cell Delivery and Integration With Diabetic Wounds to Activate Skin Tissue Regeneration.

The delayed and complicated diabetic wound healing raises clinical and social concerns. The application of stem cells along with hydrogels is an attractive therapeutic approach. However, low cell retention and integration hindered the performance. Herein, gelatin microspheres were fabricated for local delivery of adipose-derived stem cells (from rats, rADSCs), and the effect of rADSCs with microspheres on diabetic wound healing was examined. Uniform, well-dispersed microspheres were fabricated using the microfluidic technique. Due to geometry differences, the proteinase degradation rate for microspheres was four times that of the bulk hydrogel. The obtained gelatin microspheres supported cell's adhesion and proliferation and provided a suitable microenvironment for rADSC survival. For in vivo animal tests, rADSCs were labeled with CM-Dil for tracking purposes. Microspheres were well embedded in the regenerated tissue and demonstrated good biocompatibility and an adaptive biodegradation rate. Histological examination revealed rADSC-loaded gelatin microspheres that significantly accelerated wound healing via promoting M2 macrophage polarization, collagen deposition, angiogenesis associated with peripheral nerve recovery, and hair follicle formation. Notably, the relative fluorescence intensity around the hair follicle was 17-fold higher than that of the blank group, indicating rADSC participated in the healing process via exosomes. Taken together, the rADSC-laden gelatin microspheres provided a promising strategy for local stem cell delivery to improve diabetic wound healing.

A Composite of Hepatocyte Growth Factor- and 5α-Dihydrotestosterone-Gelatin Microspheres with Adipose-Derived Stem Cells Enhances Wound Healing.

INTRODUCTION: Reconstructing sebaceous glands is one goal of functionally healing patients who have suffered severe burns, instead of the simple pursuit of wound closure. Effective regeneration of skin appendages remains a challenge in skin wound management and research. OBJECTIVE: The aim of this study was to evaluate the differentiation of adipose-derived stem cells (ADSCs) into sebaceous glands and clarified the involvement of hepatocyte growth factor (HGF) and 5α-dihydrotestosterone (5α-DHT) in this process. METHODS: This study used HGF- and 5α-DHT-gelatin microspheres to treat human ADSCs and investigated the reconstruction of sebaceous glands. HGF- and 5α-DHT-gelatin microspheres were constructed using microcapsule slow-release technology. A mice full-thickness skin-wound model was established to evaluate wound healing, and hematoxylin-eosin staining was utilized to determine the skin structure. RESULTS: In vitro analyses found that HGF- and 5α-DHT-gelatin microspheres promoted migration of and tube formation by ADSCs. Furthermore, AKT/ERK signaling, which is related to sebocyte and sweat gland epithelial-cell growth, was activated after HGF and 5α-DHT treatment. An in vivo wound healing model demonstrated that ADSCs primed with amnion-loaded HGF- and 5α-DHT-gelatin microspheres promoted wound healing and increased sebaceous gland formation compared to the control group. CONCLUSIONS: This study confirms the efficacy of ADSCs treated with amnion and HGF- and 5α-DHT-gelatin microspheres in accelerating wound healing and effectively restoring sebaceous glands. This engineered tissue provides insight into and a novel therapeutic material for burns and full-thickness skin wounds.

Glucose and MMP-9 dual-responsive hydrogel with temperature sensitive self-adaptive shape and controlled drug release accelerates diabetic wound healing.

Chronic diabetic wounds are an important healthcare challenge. High concentration glucose, high level of matrix metalloproteinase-9 (MMP-9), and long-term inflammation constitute the special wound environment of diabetic wounds. Tissue necrosis aggravates the formation of irregular wounds. All the above factors hinder the healing of chronic diabetic wounds. To solve these issues, a glucose and MMP-9 dual-response temperature-sensitive shape self-adaptive hydrogel (CBP/GMs@Cel&INS) was designed and constructed with polyvinyl alcohol (PVA) and chitosan grafted with phenylboric acid (CS-BA) by encapsulating insulin (INS) and gelatin microspheres containing celecoxib (GMs@Cel). Temperature-sensitive self-adaptive CBP/GMs@Cel&INS provides a new way to balance the fluid-like mobility (self-adapt to deep wounds quickly, approximately 37 °C) and solid-like elasticity (protect wounds against external forces, approximately 25 °C) of self-adaptive hydrogels, while simultaneously releasing insulin and celecoxib on-demand in the environment of high-level glucose and MMP-9. Moreover, CBP/GMs@Cel&INS exhibits remodeling and self-healing properties, enhanced adhesion strength (39.65 ± 6.58 kPa), down-regulates MMP-9, and promotes cell proliferation, migration, and glucose consumption. In diabetic full-thickness skin defect models, CBP/GMs@Cel&INS significantly alleviates inflammation and regulates the local high-level glucose and MMP-9 in the wounds, and promotes wound healing effectively through the synergistic effect of temperature-sensitive shape-adaptive character and the dual-responsive system.

Quantifying the Compressive Force of 3D Cardiac Tissues via Calculating the Volumetric Deformation of Built-In Elastic Gelatin Microspheres.

Quantifying cardiac contractile force is of paramount important in studying mechanical heart failure and screening therapeutic drugs. However, most existing methods can only measure the in-plane component of twitch force of cardiomyocytes, such that mismatching the centripetal compressive stress of heart beating in physiology. Here, a non-destructive method is developed for quantifying the compressive stress and mapping the distribution of the local stress within the 3D cardiac tissues. In detail, elastic gelatin microspheres labeled with fluorescence beads are fabricated by microfluidic chips with high throughput, and they serve as built-in pressure sensors which are wrapped by cardiomyocytes in 3D tissues. The deformation of microspheres and the displacements of fluorescent beads induced by the contraction of cardiomyocytes are demonstrated to characterize the amount and distribution of the centripetal compressive stress. Further, the method shows a potent capability to locally quantify contractile force variation of 3D cardiac tissues, which is induced by agonist (norepinephrine) and inhibitor (blebbistatin). On the whole, the method significantly improves the 3D measurement of mechanical force in vitro and provides a solution for locally quantifying the compressive stress within engineered cardiac tissues.