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Acellular xenogeneic small vessel scaffolds preliminarily eliminate the xenogeneic antigen that could induce an immune rejection. We transplanted the Wistar rat caudal artery scaffolds into Japanese white rabbit ear central arteries, and observed the changes of blood flow and vessel wall. We acquired 30 caudal arteries from 15 Wistar rats, some were directly assigned as caudal artery group, the others were disposed by 1% p-octyl polyethelene glycol phenyl ether, and were assigned as the group of tissue engineered small vessel scaffold. We collected 15 Japanese white rabbits, and utilized a pair of ear central arteries per rabbit as hosts. Through microscopic surgery, the proximal broken end of central artery was overlapped into the donor’s proximal vessel lumen by sleeve anastomosis, while the distal broken end was sutured by classical end-to-end anastomosis. The maximum patency time of small vessel scaffold was 46 hours and 47 minutes, and which of caudal vessel was 14 hours. The poor blood flow primarily was occurred in distal broken end, while proximal end was connected in pedicle graft structure. On the 10th day, tunica intima fibers in vessel scaffold were still arranged in cylindrical conformation regularly without cell adherence. On the 100th day, tunica intima fibers were still preserved completely in proximal end. The results showed that xenogeneic acellular small vessel scaffold can be transplanted into the host, and the sleeve anastomosis was significantly superior to the classical end-to-end anastomosis.

Both mature and stem cell-derived hepatocytes lost their phenotype and functionality under conventional culture conditions. However, the 3D scaffolds containing the main extracellular matrix constitutions, such as heparin, may provide appropriate microenvironment for hepatocytes to be functional. The current study aimed to investigate the efficacy of the differentiation capability of hepatocytes derived from human Wharton’s jelly mesenchymal stem cells (WJ-MSCs) in 3D heparinized scaffold. In this case, the human WJ-MSCs were cultured on the heparinized and non-heparinized 2D collagen gels or within 3D scaffolds in the presence of hepatogenic medium. Immunostaining was performed for anti-alpha fetoprotein, cytokeratin-18 and -19 antibodies. RT-PCR was performed for detection of hepatic nuclear factor-4 (HNF-4), albumin, cytokeratin-18 and -19, glucose-6-phosphatase (G6P), c-met and Cyp2B. The results indicated that hepatogenic media induced the cells to express early liver-specific markers including HNF4, albumin, cytokeratin-18 and 19 in all conditions. The cells cultured on both heparinized culture conditions expressed late liver-specific markers such as G6P and Cyp2B as well. Besides, the hepatocytes differentiated in 3D heparinized scaffolds stored more glycogen that indicated they were more functional. Non-heparinized 2D gel was the superior condition for cholangiocyte differentiation as indicated by higher levels of cytokeratin 19 expression. In conclusion, the heparinized 3D scaffolds provided a microenvironment to mimic Disse space. Therefore, 3D heparinized collagen scaffold can be suggested as a good vehicle for hepatocyte differentiation.

The utility of a biodegradable hyaluronic acid (HyA)-based hydrogel as a tissue scaffold for intravitreal carriage of mesenchymal stem cells (MSCs) into the retina was tested. A rat model of retinal ischemia-reperfusion (IR) injury was used. DiI-labeled MSCs from three passages were loaded onto hydrogel and injected into the vitreous body of experimental and control eyeballs 1 week after IR. The neutral hydrogel was also modified to a basic pH. A control carrier, 0.01 M phosphate-buffered saline (pH 7.2; PBS) was compared. Retinal tissues were prepared 1 week and 2 weeks after MSCs application. MSCs localization and effects were evaluated on immunostained retinal preparations with confocal microscopy. MSCs localization was apparent in the retinas loaded onto hydrogels, adhering tightly to the inner limiting membrane, whereas those in PBS floated in the vitreous body. Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) were expressed in the end feet of Müller cells in the normal retina. NGF expression was slightly reduced 2 weeks IR, had expanded into the proximal processes 3 weeks IR, but it appeared reversely 1 week and 2 weeks after MSCs application, respectively. BDNF expression was higher in the ischemic and MSCs-treated ischemic retinas than in the normal and MSCs-treated control retinas, respectively. These findings demonstrate that HyA-based hydrogel is an efficient vehicle for intravitreal MSC transplantation into the retina, and that MSCs thus transplanted induce Müller glial cells to produce growth factors concerned with the survival of retinal ganglion cells.

Glaucoma, a characteristic type of optic nerve degeneration in the posterior pole of the eye, is a common cause of irreversible vision loss and the second leading cause of blindness worldwide. As an optic neuropathy, glaucoma is identified by increasing degeneration of retinal ganglion cells (RGCs), with consequential vision loss. Current treatments only postpone the development of retinal degeneration, and there are as yet no treatments available for this disability. Recent studies have shown that replacing lost or damaged RGCs with healthy RGCs or RGC precursors, supported by appropriately designed bio-material scaffolds, could facilitate the development and enhancement of connections to ganglion cells and optic nerve axons. The consequence may be an improved retinal regeneration. This technique could also offer the possibility for retinal regeneration in treating other forms of optic nerve ailments through RGC replacement. In this brief review, we describe the innovations and recent developments in retinal regenerative medicine such as retinal organoids and gene therapy which are specific to glaucoma treatment and focus on the selection of appropriate bio-engineering principles, biomaterials and cell therapies that are presently employed in this growing research area. Identification of optimal sources of cells, improving cell survival, functional integration upon transplantation, and developing techniques to deliver cells into the retinal space without provoking immune responses are the main challenges in retinal cell replacement therapies. The restoration of visual function in glaucoma patients by the RGC replacement therapies requires appropriate protocols and biotechnology methods. Tissue-engineered scaffolds, the generation of retinal organoids, and gene therapy may help to overcome some of the challenges in the generation of clinically safe RGCs.

In extensive deep dermal burn injuries, split-thickness skin graft (STSG) has been the most preferred treatment option for resurfacing burn wounds. A thick split-thickness skin graft is ideal for preventing graft contracture but is associated with delayed donor healing and the lack of adequate donor skin. When applied with STSG, the dermal substitutes offer better-reconstructed skin than STSG alone. Human-derived acellular dermal matrix (HADM) obtained from cadaver skin is a dermal equivalent with good clinical outcomes. However, high cost and limited cadaver donor skin availability limit its clinical utility. Developing a low-cost preparation method and finding an alternate source of human donated skin can help reduce the cost. The objective of this study was to explore the feasibility of making HADM from abdominoplasty panniculus skin. Skin samples were collected from the abdominoplasty panniculus of ten eligible donors with their informed consent. A combination of low-cost reagents-sodium chloride and hypotonic solution (water for injection) was used for decellularizing the skin. Characterization of the prepared Acellular Dermis Matrix prototype was done. The skin was deepidermized with one molar NaCl treatment at 37 °C for 24 h. The deepidermized dermis became acellular with hypotonic solution treatment at 4 °C for two weeks. The hematoxylin and eosin staining and cytotoxicity test confirmed the acellularity and non-cytotoxicity of the prepared HADM prototype. The HADM prototype also facilitated the formation of neo-epithelium in the 3D cell co-culture model. This study confirms that abdominoplasty panniculus can be a viable alternative for HADM preparation. Further characterization studies are required to prove the concept.

Dental pulp stem cells (DPSCs) are mesenchymal stem cells with high self-renewal potential that have the ability to differentiate into several cell types. Thus, DPSCs have become a promising source of cells for several applications in regenerative medicine, tissue engineering, and stem cell therapy. Numerous methods have been reported for the isolation, expansion, and preservation of DPSCs. However, methods are diverse and do not follow specific rules or parameters, which can affect stem cell properties, adding more variation to experimental results. In this review, we compare and analyze current experimental evidence to propose some factors that can be useful to establish better methods or improved protocols to prolong the quality of DPSCs. In addition, we highlight other factors related to biological aspects of dental tissue source (e.g., age, genetic background) that should be considered before tooth selection. Although current methods have reached significant advances, optimization is still required to improve culture stability and its maintenance for an extended period without losing stem cell properties. In addition, there is still much that needs to be done toward clinical application due to the fact that most of DPSCs procedures are not currently following good manufacturing practices. The establishment of optimized general or tailored protocols will allow obtaining well-defined DPSCs cultures with specific properties, which enable more reproducible results that will be the basis to develop effective and safe therapies.

Dermal fibroblasts play essential roles in wound healing and their dysfunction has been shown to be associated with impaired wound healing in diabetes. In the present study, we aimed at investigating whether Yes-associated protein (YAP), a mediator of mechanotransduction in dermal fibroblasts, is associated with impaired wound healing in diabetic mice. Compared with that in the control, the rate of wound contraction was decreased twofold in db/db type 2 diabetic mice (db/db mice). To mimic diabetic pathological condition, dermal fibroblasts were cultured under high glucose conditions (25.5 mM glucose). Further, dermal fibroblast-mediated contraction of wound was evaluated by in vitro collagen gel contraction assay. Dermal fibroblasts cultured under hyperglycemic condition showed impaired gel contraction and mitochondrial dysfunction, compared to the cells cultured under normoglycemic conditions (5.5 mM glucose). Importantly, compared with the normal dermal fibroblasts, diabetic db/db dermal fibroblasts expressed lower levels of growth factors and cytokines that enhance wound healing, such as insulin-like growth factor-1, stromal cell-derived factor-1, connective tissue growth factor, and transforming growth factor-β (TGF-β). The quantity of YAP mRNA was also lower in diabetic db/db dermal fibroblasts, compared with that in the control fibroblasts. These results indicate that impaired wound healing in diabetics is associated with the dysfunction of dermal fibroblasts, including downregulation of YAP, which plays essential roles in extracellular matrix remodeling and TGF-β-mediated wound healing.

Despite major progress in stem cell therapy, our knowledge of the characteristics and tissue regeneration potency of long-term transported cells is insufficient. In a previous in vitro study, we established the optimal cell transport conditions for amniotic fluid stem cells (AFSCs). In the present study, the target tissue regeneration of long-term transported cells was validated in vivo. For renal regeneration, transported AFSCs were seeded on a poly(lactide-co-glycolide) scaffold and implanted in a partially resected kidney. The target tissue regeneration of the transported cells was compared with that of freshly harvested cells in terms of morphological reconstruction, histological microstructure reformation, immune cell infiltration, presence of induced cells, migration into remote organs, expression of inflammation/fibrosis/renal differentiation-related factors, and functional recovery. The kidney implanted with transported cells showed recovery of total kidney volume, regeneration of glomerular/renal tubules, low CD4/CD8 infiltration, and no occurrence of cancer during 40 weeks of observation. The AFSCs gradually disappeared and did not migrate into the liver, lung, or spleen. We observed low expression levels of pro-inflammatory cytokines and fibrotic factors; enhanced expression of the genes Wnt4, Pax2, Wt1, and Emx2; and significantly reduced blood urea nitrogen and creatinine values. There were no statistical differences between the performance of freshly harvested cells and that of the transported cells. This study demonstrates that long-term transported cells under optimized conditions can be used for cell therapy without adverse effects on stem cell characteristics, in vivo safety, and tissue regeneration potency.