Collagen type II solution extracted from supercritical carbon dioxide decellularized porcine cartilage: regenerative efficacy on post-traumatic osteoarthritis model.

Osteoarthritis (OA) of the knee is a common degenerative articular disorder and is one of the main causes of pain and functional disability. Cartilage damage is frequently linked to elevated osteoarthritis incidence. Supercritical carbon dioxide (scCO2) decellularized cartilage graft produced from the porcine cartilage is an ideal candidate for cartilage tissue engineering. In the present study, we derived collagen type II (Col II) solution from the scCO2 decellularized porcine cartilage graft (dPCG) and compared its efficacy with hyaluronic acid (HA) in the surgical medial meniscectomy (MNX) induced post-traumatic osteoarthritis (PTOA) model. Dose-dependent attenuation of the OA (12.3 ± 0.8) progression was observed in the intra-articular administration of Col II solution (7.3 ± 1.2) which significantly decreased the MNX-induced OA symptoms similar to HA. The pain of the OA group (37.4 ± 2.7) was attenuated dose-dependently by Col II solution (45.9 ± 4.1) similar to HA (43.1 ± 3.5) as evaluated by a capacitance meter. Micro-CT depicted a dose-dependent attenuation of articular cartilage damage by the Col II solution similar to HA treatment. A significant (p < 0.001) dose-dependent elevation in the bone volume was also observed in Col II solution-treated OA animals. The protective competence of Col II solution on articular cartilage damage is due to its significant (p < 0.001) increase in the expression of type II collagen, aggrecan and SOX-9 similar to HA. To conclude, intra-articular administration of type II collagen solution and HA reestablished the injured cartilage and decreased osteoarthritis progression in the experimental PTOA model.

Supercritical carbon dioxide-decellularized arteries exhibit physiologic-like vessel regeneration following xenotransplantation in rats.

Currently, many techniques are used for decellularization of grafts, including physical, enzymatic, and chemical treatments. Indeed, decellularized xenogenic grafts provide superior outcomes than alternative synthetic conduits. However, vascular grafts produced by these methods are not perfect; their defects include defective vessel wall structures, detergent residues, and the development of aneurysms after grafting. Therefore, it is essential to develop a more appropriate process to produce decellularized vascular grafts. Supercritical carbon dioxide (ScCO2) has been used in decellularization technologies in recent years. It is beneficial for the long-term preservation of tissues and regeneration of new vessels. We have previously reported that ScCO2-produced acellular porcine corneas show excellent biocompatibility following lamellar corneal transplantation in rabbits. In this study, we wanted to use this method to fabricate vascular grafts (ScCO2-decellularized rabbit femoral artery (DFA)) and analyze their efficacy, parameters regarding rejection by the recipient's (ACI/NKyo rats) immune system and biocompatibility, structural regeneration, and functionality in vivo. The results indicated that the ScCO2-DFA showed higher biocompatibility, enhanced chemotactic migration of endothelial progenitor cells, lower risk of vasculopathy, lower inflammatory and splenic immune responses, and better physiological-like tension responses after xenotransplantation (XTP) in ACI/NKyo rats compared with the results obtained after XTP using detergent decellularized vascular grafts (SDS-DFA). In conclusion, ScCO2 is an excellent decellularization technique in the fabrication of biocompatible vascular grafts and has tremendous application in vascular regenerative medicine.

Regenerative Efficacy of Supercritical Carbon Dioxide-Derived Bone Graft Putty in Rabbit Bone Defect Model.

Bone defects can arise from numerous reasons, such as aging, tumor, trauma, infection, surgery, and congenital diseases. Bone grafts are commonly used as a substitute to fill the void and regenerate the defect. Due to its clean and green technology, the supercritical carbon dioxide (SCCO2) extraction aided the production of bone grafts is a recent trend. The SCCO2-derived bone graft has osteoconductive and osteoinductive properties along with excellent biocompatible, nontoxic, bioabsorbable, osteoconductive, and good mechanical properties; however, clinical usage during surgery is time-consuming. Therefore, we produced a putty material combining bone graft powder and acellular dermal matrix (ADM) powder and tested its regenerative efficacy in the critical defect in the rabbit model. The putty was found to retain the tubular structure. In addition, the putty depicted excellent stickiness and cohesiveness in both saline and blood medium. The bone regeneration of bone graft and putty was similar; both had excellent bone healing and regeneration of critical defects as evaluated by the X-ray, microtomography, hematoxylin-eosin, Masson trichrome, and alizarin red staining. Putty contains a less washout rate, good mechanical strength, and biocompatibility. In conclusion, the SCCO2-derived moldable putty could be a promising easy-to-use alternative for bone grafts at present which might have real-world usage in orthopedics as a potential bone void filler and dental socket preservation.

Supercritical Carbon Dioxide Decellularized Xenograft-3D CAD/CAM Carved Bone Matrix Personalized for Human Bone Defect Repair.

About 30-50% of oral cancer patients require mandibulectomy and autologous fibula reconstruction. Autograft is the gold standard choice because of its histocompatibility; however, it requires additional surgery from the patient and with possible complications such as loss of fibula leading to calf weakening in the future. Allograft and xenograft are alternatives but are susceptible to immune response. Currently, no personalized bone xenografts are available in the market for large fascial bone defects. In addition, a large-sized complex shape bone graft cannot be produced directly from the raw material. We propose the use of porcine bones with 3D CAD/CAM carving to reconstruct a personalized, wide range and complex-shaped bone. We anticipate that patients can restore their native facial appearance after reconstruction surgery. Supercritical CO2 (SCCO2) technology was employed to remove the cells, fat and non-collagenous materials while maintaining a native collagen scaffold as a biomedical device for bone defects. We successfully developed 3D CAD/CAM carved bone matrices, followed by SCCO2 decellularization of those large-sized bones. A lock-and-key puzzle design was employed to fulfil a wide range of large and complex-shaped maxillofacial defects. To conclude, the 3D CAD/CAM carved bone matrices with lock and key puzzle Lego design were completely decellularized by SCCO2 extraction technology with intact natural collagen scaffold. In addition, the processed bone matrices were tested to show excellent cytocompatibility and mechanical stiffness. Thus, we can overcome the limitation of large size and complex shapes of xenograft availability. In addition, the 3D CAD/CAM carving process can provide personalized tailor-designed decellularized bone grafts for the native appearance for maxillofacial reconstruction surgery for oral cancer patients and trauma patients.

Acellular Porcine Cornea Produced by Supercritical Carbon Dioxide Extraction: A Potential Substitute for Human Corneal Regeneration.

PURPOSE: The aim of this study was to develop a non-cytotoxic, biocompatible innovative acellular porcine cornea (APC) for corneal wound healing and corneal blindness treatment. METHODS: APC was produced by using supercritical carbon dioxide (SCCO2) to decellularize the porcine cornea. Decellularization of the porcine cornea was examined by hematoxylin and eosin staining and 4,6-diamidino-2-phenylindole, dihydrochloride staining. The residual DNA content of APC was analyzed in comparison with the native porcine cornea. Virus inactivation up to at least 6 log10 was confirmed for the stepwise process of APC for 4 different model viruses. In addition, a series of in vitro and in vivo tests in accordance with ISO-10993 biocompatibility assay and animal performance tests were performed. RESULTS: APC produced by the SCCO2 process revealed complete decellularization, without any residual non-collagenous proteins. The scanning electron microscopy structural features of the decellularized cornea were similar to those of human. APC was found to be nontoxic and exhibited excellent biocompatibility in both in vitro and in vivo studies. The animal performance test proved that APC exerted excellent adaptability on the cornea and no sign of irritation and good compatibility in lamellar corneal transplantation. CONCLUSIONS: APC manufactured by SCCO2 technology revealed complete cells and non-collagenous protein removal compared with the Triton-sodium dodecyl sulfate decellularization process. APC showed excellent biocompatibility in rabbit lamellar corneal transplantation with a follow-up to 1 year. APC can be a potential substitute for human-donated cornea for corneal transplantation in the near future.

Supercritical Carbon Dioxide Decellularized Bone Matrix Seeded with Adipose-Derived Mesenchymal Stem Cells Accelerated Bone Regeneration.

Large bone fractures with segmental defects are a vital phase to accelerate bone integration. The present study examined the role of supercritical carbon dioxide (scCO2) decellularized bone matrix (scDBM) seeded with allogeneic adipose-derived mesenchymal stem cells (ADSC) as bio-scaffold for bone regeneration. Bio-scaffold produced by seeding ADSC to scDBM was evaluated by scanning electron microscopy (SEM). Rat segmental femoral defect model was used as a non-union model to investigate the callus formation in vivo. Histological analysis and osteotomy gap closure in the defect area were analyzed at 12 and 24 weeks post-surgery. Immunohistochemical expression of Ki-67, BMP-2 and osteocalcin was evaluated to assess the ability of new bone formation scDBM. ADSC was found to attach firmly to scDBM bioscaffold as evidenced from SEM images in a dose-dependent manner. Callus formation was observed using X-ray bone imaging in the group with scDBM seeded with 2 × 106 and 5 × 106 ASCs group at the same time-periods. H&E staining revealed ASCs accelerated bone formation. IHC staining depicted the expression of Ki-67, BMP-2, and osteocalcin was elevated in scDBM seeded with 5 × 106 ASCs group at 12 weeks after surgery, relative to other experimental groups. To conclude, scDBM is an excellent scaffold that enhanced the attachment and recruitment of mesenchymal stem cells. scDBM seeded with ASCs accelerated new bone formation.

Reconstruction of the orbital floor using supercritical CO2 decellularized porcine bone graft.

Orbital floor fractures subsequently lead to consequences such as diplopia and enophthalmos. The graft materials used in orbital floor fractures varied from autografts to alloplastic grafts, which possess certain limitations. In the present study, a novel porcine bone matrix decellularized by supercritical CO2 (scCO2), ABCcolla® Collagen Bone Graft, was used for the reconstruction of the orbital framework. The study was approved by the institutional review board (IRB) of Kaohsiung Medical University Chung-Ho Memorial Hospital (KMUH). Ten cases underwent orbital floor reconstruction in KMUH in 2019. The orbital defects were fixed by the implantation of the ABCcolla® Collagen Bone Graft. Nine out of ten cases used 1 piece of customized ABCcolla® Collagen Bone Graft in each defect. The other case used 2 pieces of customized ABCcolla® Collagen Bone Graft in one defect area due to the curved outline of the defect. In the outpatient clinic, all 10 cases showed improvement of enophthalmos on CT (computerized tomography) at week 8 follow-up. No replacement of implants was needed during follow-ups. To conclude, ABCcolla® Collagen Bone Graft proved to be safe and effective in the reconstruction of the orbital floor with high accessibility, high stability, good biocompatibility, low infection rate and low complication rate.

Supercritical carbon dioxide decellularized porcine cartilage graft with PRP attenuated OA progression and regenerated articular cartilage in ACLT-induced OA rats.

Knee osteoarthritis (OA) is a common degenerative articular disorder and considered one of the primary causes of pain and functional disability. Knee OA is prevalent in 10% of men and 13% of women aged 60 years above. The study aims to use cartilage tissue engineering that combines the triads of decellularized porcine cartilage graft as "scaffold," plasma rich platelet (PRP) as "signal" and chondrocytes from rat as "cell" to attenuate ACLT-induced OA progression and regenerate the knee cartilage in rats. Decellularization of the porcine cartilage was characterized by hematoxylin and eosin, 4,6-Diamidino-2-phenylindole staining, scanning electron microscopy and residual DNA quantification. The protective effect of decellularized porcine cartilage graft (dPCG) was evaluated by intra-articular administration in surgically induced anterior cruciate ligament transection (ACLT) rat osteoarthritis (OA) model. Supercritical carbon dioxide technology completely decellularized the porcine cartilage. Intra-articular administration of dPCG with or without PRP significantly reduced the ACLT-induced OA symptoms and attenuated the OA progression. Pain-relief by dPCG with or without PRP was assessed by capacitance meter and improved articular cartilage damage in the rat knee was characterized by X-ray and micro-CT. Besides, the histological analysis depicted cartilage protection by dPCG with or without PRP. The repairation and attenuation effect by dPCG with or without PRP in the articular knee cartilage damage were also explored by safranin-O, type II collagen, aggrecan and SOX-9 immuno-staining. To conclude, intra-articular administration of dPCG with or without PRP is efficient in repairing the damaged cartilage in the experimental OA model.

A novel 3D histotypic cartilage construct engineered by supercritical carbon dioxide decellularized porcine nasal cartilage graft and chondrocytes exhibited chondrogenic capability in vitro.

Augmentative and reconstructive rhinoplasty surgical procedures use autologous tissue grafts or synthetic grafts to repair the nasal defect and aesthetic reconstruction. Donor site trauma and morbidity are common in autologous grafts. The desperate need for the production of grafted 3D cartilage tissues as rhinoplasty grafts without the adverse effect is the need of the hour. In the present study, we developed a bioactive 3D histotypic construct engineered with the various ratio of adipose-derived stem cells (ADSC) and chondrocytes together with decellularized porcine nasal cartilage graft (dPNCG). We decellularized porcine nasal cartilage using supercritical carbon dioxide (SCCO2) extraction technology. dPNCG was characterized by H&E, DAPI, alcian blue staining, scanning electron microscopy and residual DNA content, which demonstrated complete decellularization. 3D histotypic constructs were engineered using dPNCG, rat ADSC and chondrocytes with different percentage of cells and cultured for 21 days. dPNCG together with 100% chondrocytes produced a solid mass of 3D histotypic cartilage with significant production of glycosaminoglycans. H&E and alcian blue staining showed an intact mass, with cartilage granules bound to one another by extracellular matrix and proteoglycan, to form a 3D structure. Besides, the expression of chondrogenic markers, type II collagen, aggrecan and SOX-9 were elevated indicating chondrocytes cultured on dPNCG substrate facilitates the synthesis of type II collagen along with extracellular matrix to produce 3D histotypic cartilage. To conclude, dPNCG is an excellent substrate scaffold that might offer a suitable environment for chondrocytes to produce 3D histotypic cartilage. This engineered 3D construct might serve as a promising future candidate for cartilage tissue engineering in rhinoplasty.

Development of a decellularized porcine bone graft by supercritical carbon dioxide extraction technology for bone regeneration.

A series of novel decellularized porcine collagen bone graft (DPB) materials in a variety of shapes and sizes were developed by the supercritical carbon dioxide (SCCO2 ) extraction technique. The complete decellularization of DPB was confirmed by hematoxylin and eosin staining, 4,6-diamidino-2-phenylindole (DAPI) staining, and residual DNA analysis. The native intact collagen remained in the DPB after the SCCO2 process was confirmed by Masson trichrome staining. The physicochemical characteristics of DPB were investigated by scanning electron microscopy and x-ray diffraction. The cytotoxicity and biocompatibility tests according to ISO10993 and its efficacy for bone regeneration in osteochondral defects in rabbits were evaluated. The rabbit pyrogen test confirmed DPB was non-toxic. In vitro and in vivo biocompatibility tests of the DPB did not show any toxic or mutagenic effects. The bone regeneration potential of the DPB presented no significant histological differences compared to commercially available deproteinized bovine bone. In conclusion, DPB produced by SCCO2 exhibited similar chemical characteristics to human bone, no toxicity, good biocompatibility, and enhanced bone regeneration in rabbits comparable to that of deproteinized bovine bone. Results from this study could shed light on the potential application of the SCCO2 extraction technique to generate a native decellularized scaffold for bone tissue regeneration in human clinical trials.

3D composite engineered using supercritical CO2 decellularized porcine cartilage scaffold, chondrocytes, and PRP: Role in articular cartilage regeneration.

At present, no definitive treatment for articular cartilage defects has been perfected. Most of the previous treatments involved multiple drilling and microfracture over defect sites with repair-related substances, which poses a limited therapeutic effect. End-stage therapy includes artificial knee joint replacement. In this study, we prepared a novel decellularized natural cartilage scaffold from porcine articular cartilage by supercritical CO2 extraction technology and three-dimensional (3D) composites made using decellularized porcine cartilage graft (dPCG) as scaffolds, platelet-rich plasma (PRP), thrombin as signals and chondrocytes as cells for the treatment of articular cartilage defects. In this study, in vitro and in vivo cartilage regeneration and the expression of chondrogenic markers were examined. Decellularized cartilage graft (dPCG) was evaluated for the extent of cell and DNA removal. Residual cartilage ECM structure was confirmed to be type II collagen by SDS PAGE and immunostaining. The new 3D composite with dPCG (100 mg and 2 × 106 chondrocytes) scaffold promotes chondrogenic marker expression in vitro. We found that the in vivo 3D composite implanted cartilage defect showed significant regeneration relative to the blank and control implant. Immunohistochemical staining showed increase of expression including Collagen type II and aggrecan in 3D composite both in vitro and in vivo studies. In this study, the bioengineered 3D composite by combining dPCG scaffold, chondrocytes, and PRP facilitated the chondrogenic marker expression in both in vitro and in vivo models with accelerated cartilage regeneration. This might serve the purpose of clinical treatment of large focal articular cartilage defects in humans in the near future.

Evaluating the bone-regenerative role of the decellularized porcine bone xenograft in a canine extraction socket model.

OBJECTIVE: To evaluate the efficacy of a novel decellularized porcine bone xenograft, produced by supercritical carbon dioxide extraction technology, on alveolar socket healing after tooth extraction compared to a commercially available deproteinized bovine bone (Bio-Oss®). MATERIALS AND METHODS: Nine dogs (about 18 months old and weighing between 20 kg and 30 kg) underwent extractions of lower second to fourth premolars, bilaterally. The dogs were randomly selected and allocated to the following groups: Group 1: control unfilled socket; Group 2: socket filled with decellularized porcine bone xenograft (ABCcolla®) and covered by a commercially available porcine collagen membrane (Bio-Gide®); Group 3: socket filled with Bio-Oss® and covered by Bio-Gide® membrane. One dogs from each group was sacrificed at 4-, 12-, and 24-week to evaluate the socket healing after tooth extraction. The mandible bone blocks were processed without decalcification and specimens were embedded in methyl methacrylate and subjected to histopathology analyses to evaluate the bone regeneration in the extraction sockets. RESULTS: At 24-week after socket healing, ABCcolla® treated defects demonstrated significantly higher histopathology score in new bone formation and bone bridging, but significantly lower score in fluorescent labeling than those of the Bio-Oss®. In the microphotographic examination, decellularized porcine bone xenograft showed similar characteristics of new bone formation to that of Bio-Oss®. However, there was significantly less remnant implant materials in the decellularized porcine bone xenograft compared to the Bio-Oss® group at 24-week. Thus, the decellularized porcine bone graft seems to have promising bone regeneration properties similar to that of Bio-Oss® with less remnant grafted material in a canine tooth extraction socket model. CONCLUSIONS: Within the limits of the study, we concluded that ABCcolla® treated defects demonstrated significantly more new bone formation and better bone bridging, but less amount of fluorescent labeling than those of the Bio-Oss® group. However, clinical studies in humans are recommended to confirm these findings.

Protocols for the preparation and characterization of decellularized tissue and organ scaffolds for tissue engineering.

Extracellular matrix (ECM) scaffolds are extensively used in tissue engineering studies and numerous clinical applications for tissue and organ reconstructions. Due to the global severe shortage of human tissues and organs, xenogeneic biomaterials are a common source for human tissue engineering and regenerative medicine applications. Traditional methods for decellularization often disrupt the 3D architecture and damage the structural integrity of the ECM scaffold. To efficiently obtain natural ECM scaffolds from animal tissues and organs with intact architecture, we have developed a platform decellularization process using supercritical CO2 and tested its potential application in tissue engineering. A combination of human mesenchymal stem cells with a decellularized dermal matrix scaffold allowed complete regeneration of skin structure in a porcine full-thickness wound model.

Protocols for accelerated production and purification of collagen scaffold and atelocollagen from animal tissues.

Traditional purification of atelocollagen involves a harsh extraction process with environment-polluting chemicals and costly and/or time-consuming procedures which include salting-out, alkali, acid and enzymatic treatment and ion-exchange chromatography. The atelocollagen market is growing exponentially, with demand in the skincare industry and for various medical applications. As a result, there is an urgent need for an eco-friendly production process with minimal manipulation. We developed a novel technique involving supercritical carbon dioxide extraction technology to remove the cells and noncollagenous substances from the porcine hide. Subsequent processes allow the production of several products, including decellularized dermal membrane, high-purity collagen particles and atelocollagen. The advantages of our process are its faster speed and lower environmental impact and its generation of multiple products, including high purity atelocollagen with complete removal of telopeptides.

Supercritical Carbon Dioxide-decellularized Porcine Acellular Dermal Matrix combined with Autologous Adipose-derived Stem Cells: Its Role in Accelerated Diabetic Wound Healing.

Diabetes mellitus (DM) causes impaired wound healing by affecting one or more of the biological mechanisms of hemostasis, inflammation, proliferation, and remodeling and a large number of cell types, extracellular components, growth factors, and cytokines. Interventions targeted toward these mechanisms might accelerate the wound healing process. To evaluate the wound healing efficacy of supercritical carbon dioxide (scCO2)-decellularized porcine acellular dermal matrix (ADM) combined with autologous adipose-derived stem cells (ASCs) in streptozotocin (STZ)-induced DM rats. DM was induced by injecting rats with STZ; dorsal full-thickness skin (5 × 5 cm2) was created and treated with and without ASCs-scCO2-treated ADM to evaluate the wound healing rate through histological examination, fluorescence microscopic observation, and immunohistochemical analysis. In the present study, complete decellularization of the porcine dermal matrix was achieved through scCO2. Isolation of ASCs was conducted and evaluated using CD29+/CD31-/CD45-/CD90+ markers in flow cytometry, which indicated that more than 90% of cells were ASCs. The percentage of cells labeled with CD29+ and CD90+ was found to be 97.50% and 99.69%, respectively. The wound healing rate increased in all groups relative to the group with the DM wound without treatment. DM wound treated with ADM-ASCs showed significantly higher (p < 0.01) wound healing rate than DM wound without treatment. ADM-ASC-treated rats showed significantly increased epidermal growth factor, Ki67, and prolyl 4-hydroxylase and significantly decreased CD45 compared with the group with the DM wound without treatment. The intervention comprising ADM decellularized from porcine skin by using scCO2 and ASCs was proven to improve diabetic wound healing. ADM-ASCs had a positive effect on epidermal regeneration, anti-inflammation, collagen production and processing, and cell proliferation; thus, it accelerated wound healing.

Preparation of acellular scaffold for corneal tissue engineering by supercritical carbon dioxide extraction technology.

In this study, we developed a novel method using supercritical carbon dioxide (SCCO2) to prepare acellular porcine cornea (APC). Under gentle extraction conditions using SCCO2 technology, hematoxylin and eosin staining showed that cells were completely lysed, and cell debris, including nuclei, was efficiently removed from the porcine cornea. The SCCO2-treated corneas exhibited intact stromal structures and appropriate mechanical properties. Moreover, no immunological reactions and neovascularization were observed after lamellar keratoplasty in rabbits. All transplanted grafts and animals survived without complications. The transplanted APCs were opaque after the operation but became transparent within 2weeks. Complete re-epithelialization of the transplanted APCs was observed within 4weeks. In conclusion, APCs produced by SCCO2 extraction technology could be an ideal and useful scaffold for corneal tissue engineering. STATEMENT OF SIGNIFICANCE: We decellularized the porcine cornea using SCCO2 extraction technology and investigated the characteristics, mechanical properties, and biocompatibility of the decellularized porcine cornea by lamellar keratoplasty in rabbits. To the best of our knowledge, this is the first report describing the use of SCCO2 extraction technology for preparation of acellular corneal scaffold. We proved that the cellular components of porcine corneas had been efficiently removed, and the biomechanical properties of the scaffold were well preserved by SCCO2 extraction technology. SCCO2-treated corneas maintained optical transparency and exhibited appropriate strength to withstand surgical procedures. In vivo, the transplanted corneas showed no evidence of immunological reactions and exhibited good biocompatibility and long-term stability. Our results suggested that the APCs developed by SCCO2 extraction technology could be an ideal and useful scaffold for corneal replacement and corneal tissue engineering.

Injected Implant of Uncultured Stromal Vascular Fraction Loaded Onto a Collagen Gel: In Vivo Study of Adipogenesis and Long-term Outcomes.

BACKGROUND: Stromal vascular fraction (SVF) cells were used to increase the efficacy of a newly formed adipose tissue in a collagen gel in vitro. However, the outcome of the seeded cells in the collagen gel in vivo remains unknown. We traced the SVF cells in the host tissue and evaluated the efficacy of SVF for fat tissue engineering. METHODS: The aggregates implanted in the experimental and control groups were prepared by mixing SVF with the collagen gel and Dulbecco's modified Eagle medium with the collagen gel, respectively. The aggregates were implanted using a subcutaneous injection into the backs of immunodeficient mice. The aggregates were harvested 1, 2, 4, and 6 months after implantation; and 9 mice were euthanized each time. Macroscopic changes in the volume and wet weight of the aggregates were assessed. The formation of adipose tissue was studied using hematoxylin and eosin and Nile red staining. The origin and survival of adipocytes in the aggregates were examined through the immunostaining of leptin antibodies, DNA assay, and tracing of SVF cells by 1,1'-dioctadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate labeling. RESULTS: The formation of adipose tissue was observed in all of the aggregates. Implanted human SVF cells remained in the experimental aggregates harvested after 1, 2, and 4 months but not after 6 months. At 6 months, viable adipocytes in both groups were of murine origin. Furthermore, at 6 months, the mean volume of the aggregate (P < 0.001) and the mean percentage of adipocytes (P < 0.001) were significantly higher in the experimental group than in the control group. CONCLUSIONS: Implanted SVF cells could not be traced in the aggregates harvested at 6 months but promoted the recruitment of host adipocytes to generate more adipose tissue in the experimental group than in the control group.

Tailored design of electrospun composite nanofibers with staged release of multiple angiogenic growth factors for chronic wound healing.

The objective of this research study is to develop a collagen (Col) and hyaluronic acid (HA) inter-stacking nanofibrous skin equivalent substitute with the programmable release of multiple angiogenic growth factors (vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) and endothelial growth factor (EGF)) either directly embedded in the nanofibers or encapsulated in the gelatin nanoparticles (GNs) by electrospinning technology. The delivery of EGF and bFGF in the early stage is expected to accelerate epithelialization and vasculature sprouting, while the release of PDGF and VEGF in the late stage is with the aim of inducing blood vessels maturation. The physiochemical characterizations indicate that the Col-HA-GN nanofibrous membrane possesses mechanical properties similar to human native skin. The design of a particle-in-fiber structure allows growth factors for slow controlled release up to 1month. Cultured on biodegradable Col-HA membrane with four kinds of growth factors (Col-HA w/4GF), endothelial cells not only increase in growth rate but also form a better network with a thread-like tubular structure. The therapeutic effect of Col-HA w/4GF membrane on streptozotocin (STZ)-induced diabetic rats reveals an accelerated wound closure rate, together with elevated collagen deposition and enhanced maturation of vessels, as revealed by Masson's trichrome stain and immunohistochemical analysis, respectively. From the above, the electrospun Col-HA-GN composite nanofibrous skin substitute with a stage-wise release pattern of multiple angiogenic factors could be a promising bioengineered construct for chronic wound healing in skin tissue regeneration.

Characterization and spinal fusion effect of rabbit mesenchymal stem cells.

BACKGROUND: The surface markers of mesenchymal stem cells (MSCs) of rabbits have been reported only sporadically. However, interest in the spinal fusion effect of MSCs has risen recently. The purpose of this research was to study the surface markers and spinal fusion effect of rabbit MSCs. RESULTS: Of our rabbit MSCs, 2% expressed CD14, CD29, and CD45, 1% expressed CD90 and 97% expressed CD44. These results implied the MSCs were negative for CD14, CD29, CD45, and CD90, but positive for CD44. The surgical results showed that satisfactory fusion occurred in 10 rabbits (83%) in the study group and unsatisfactory fusion in 2 (17%). In the control group, satisfactory fusion was found in 3 rabbits (25%) and unsatisfactory fusion in 9 (75%). Statistical analysis showed the study group had significantly better spinal fusion results than the control group. CONCLUSIONS: The surface markers of human and rabbit MSCs are not exactly the same. Rabbit MSCs do not have positive reactivity for CD29 and CD90, which are invariably present on human MSCs. The allogeneic undifferentiated rabbit MSCs were able to promote spinal fusion and did not induce an adverse immune response.