Chemokine SDF1 Mediated Bone Regeneration Using Biodegradable Poly(D,L-lactide-co-glycolide) 3D Scaffolds and Bone Marrow-Derived Mesenchymal Stem Cells: Implication for the Development of an "Off-the-Shelf" Pharmacologically Active Construct.

There is an increasing need for bone substitutes for reconstructive orthopedic surgery following removal of bone tumors. Despite the advances in bone regeneration, the use of autologous mesenchymal stem cells (MSC) presents a significant challenge, particularly for the treatment of large bone defects in cancer patients. This study aims at developing new chemokine-based technology to generate biodegradable scaffolds that bind pharmacologically active proteins for regeneration/repair of target injured tissues in patients. Primary MSC were cultured from the uninvolved bone marrow (BM) of cancer patients and further characterized for "stemness". Their ability to differentiate into an osteogenic lineage was studied in 2D cultures as well as on 3D macroporous PLGA scaffolds incorporated with biomacromolecules bFGF and homing factor chemokine stromal-cell derived factor-1 (SDF1). MSC from the uninvolved BM of cancer patients exhibited properties similar to that reported for MSC from BM of healthy individuals. Macroporous PLGA discs were prepared and characterized for pore size, architecture, functional groups, thermostability, and cytocompatibility by ESEM, FTIR, DSC, and CCK-8 dye proliferation assay, respectively. It was observed that the MSC+PLGA+bFGF+SDF1 construct cultured for 14 days supported significant cell growth, osteo-lineage differentiation with increased osteocalcin expression, alkaline phosphatase secretion, calcium mineralization, bone volume, and soluble IL6 compared to unseeded PLGA and PLGA+MSC, as analyzed by confocal microscopy, biochemistry, ESEM, microCT imaging, flow cytometry, and EDS. Thus, chemotactic biomacromolecule SDF1-guided tissue repair/regeneration ability of MSC from cancer patients opens up the avenues for development of "off-the-shelf" pharmacologically active construct for optimal repair of the target injured tissue in postsurgery cancer patients, bone defects, damaged bladder tissue, and radiation-induced skin/mucosal lesions.

Evaluating KIND1 human embryonic stem cell-derived pancreatic progenitors to ameliorate streptozotocin-induced diabetes in mice.

BACKGROUND & OBJECTIVES: Diabetes is a global disease burden. Various stem cell types are being explored to serve as an alternative source of islets. This study was conducted to evaluate the ability of in-house developed human embryonic stem (hES) cells-derived pancreatic progenitors to ameliorate diabetic symptoms in mice. METHODS: Pancreatic progenitors were packed in macro-capsules and transplanted into six male Swiss mice and four mice were taken as controls. Thirty days post-transplantation, diabetes was induced by streptozotocin treatment. Mice were then followed up for >100 days and body weight and blood glucose levels were regularly monitored. RESULTS: Control mice lost weight, maintained high glucose levels and did not survive beyond 40 days, whereas transplanted group maintained body weight and four of the six mice had lowered blood glucose levels. About five-fold increase was observed in human C-peptide levels in the recipients of progenitor transplants as compared to diabetic control. INTERPRETATION & CONCLUSIONS: The beneficial effect of transplanted cells was not long-lasting. Further studies are required to critically evaluate and compare the potential of endogenous pluripotent stem cells and hES cells-derived progenitors before moving from bench to the bedside.

Antibacterial nanosilver coated orthodontic bands with potential implications in dentistry.

BACKGROUND & OBJECTIVES: Fixed orthodontic treatment, an indispensable procedure in orthodontics, necessitates insertion of dental bands. Insertion of band material could also introduce a site of plaque retention. It was hypothesized that band materials with slow-release antimicrobial properties could help in sustained infection control, prevention of dental plaque formation and further associated health risks. Considering the known antimicrobial proprieties of silver, a coating of silver nanoparticle (SNP) onto the stainless steel bands was done and characterized for its beneficial properties in the prevention of plaque accumulation. METHODS: Coatings of SNPs on conventional stainless steel dental bands were prepared using thermal evaporation technology. The coated dental bands were characterized for their physicochemical properties and evaluated for antimicrobial activity and biocompatibility. The physiochemical characterization of band material both coated and uncoated was carried out using scanning electron microscope, energy dispersive spectroscopy, atomic force microscopyand contact angle test. Biocompatibility tests for coated band material were carried using L929 mouse fibroblast cell culture and MTT [3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide] assay. Antimicrobial activity of coated band material against Gram-positive bacteria was tested. RESULTS: A stable and uniform coating of SNPs was obtained. The coated band materials were biocompatible as well as possessed distinct antimicrobial activity. INTERPRETATION & CONCLUSIONS: The SNP coated dental bands could be potential antimicrobial dental bands for future clinical use. Further studies need to be done to validate the efficiency of coated band materials in oral environments.

Pulmonary surfactant expression analysis--role of cell-cell interactions and 3-D tissue-like architecture.

Surfactant production is important in maintaining alveolar function both in vivo and in vitro, but surfactant expression is the primary property lost by alveolar Type II Pneumocytes in culture and its maintenance is a functional requirement. To develop a functional tissue-like model, the in vivo cell-cell interactions and three dimensional architecture has to be reproduced. To this end, 3D button-shaped synthetic gelatin vinyl acetate (GeVAc) co-polymer scaffold was seeded with different types of lung cells. Functionality of the construct was studied under both static and dynamic conditions. The construct was characterized by Environmental Scanning Electron and fluorescent microscopy, and functionality of the system was analyzed by studying mRNA modulations of all four surfactant genes A, B, C, and D by real time-PCR and varying culture conditions. The scaffold supports alveolar cell adhesion and maintenance of cuboidal morphology, and the alveolar-specific property of surfactant synthesis, which would otherwise be rapidly lost in culture. This is a novel 3D system that expresses all 4 surfactants for a culture duration of 3 weeks.

Polyhedral oligomeric silsesquioxane-F68 hybrid vesicles for folate receptor targeted anti-cancer drug delivery.

Polyhedral Oligomeric Silsesquioxane (POSS)-F68 hybrid vesicles with an average diameter of 700 nm are produced using a stable solution of heterofunctional POSS having 3-aminopropyl and vinyl groups and pluronic F68 in ethanol-water mixture. Thermogram and zeta potential values evidence the spontaneous self-assembly of POSS into bilayers through H-bonding interaction between the aminopropyl groups, and the effective stabilization of the POSS-bilayers by amphiphilic F68 during solvent-evaporation to form the vesicles. The vesicles are noncytotoxic and dispersible in aqueous solvents through steric stabilization provided by the hydrophilic F68. A highly facile coinclusion method has been used for making doxorubicin and folic acid loaded vesicles. Doxorubicin loaded in the vesicles exhibits a controlled release profile in phosphate buffered saline. Confocal microscopic and flow cytometric studies on the endocytosis of the vesicles by HeLa and HOS cells prove that a noncovalent entrapment of excess folic acid in the vesicles through H-bonding is sufficient to enhance the uptake significantly. POSS-F68 vesicles in combination with folic acid and a chemotherapeutic can have potential for targeted intracellular anti-cancer drug delivery.

Enhanced encapsulation of chondrocytes within a chitosan/hyaluronic acid hydrogel: a new technique.

Two encapsulation techniques for rabbit chondrocytes in chitosan/hyaluronic acid gel have been compared. The standard technique involves the cross-linking of chitosan and hyaluronic acid at 2:1 (w/w). In the modified technique, cells were initially added to 33% of hyaluronic acid dialdehyde and the gelation process was completed with the remaining 67%. This minimised the cell loss and improved the encapsulation of the cells. By the third week, the modified technique showed better seeding density, with matrix synthesis (per scaffold) of 11 µg as compared to 1.1 µg in the current technique. Relative expression of collagen II with the current technique and the modified technique were 6.4% and ~1,600% respectively. The modified technique was superior for matrix synthesis and maintenance of phenotype.

Transplantation of islet-like cell clusters derived from human dental pulp stem cells restores normoglycemia in diabetic mice.

BACKGROUND AIMS: The success of islet transplantation for diabetes depends on the availability of an adequate number of allogeneic or autologous islets. Postnatal stem cells are now considered for the generation of physiologically competent, insulin-producing cells. Our group showed earlier that it is possible to generate functional islets from human dental pulp stem cells by using a serum-free cocktail in a three-step protocol. METHODS: We compared the yield of generated islet-like cell clusters (ICCs) from stem cells from pulps of human exfoliated deciduous teeth (SHED) and dental pulp stem cells from permanent teeth (DPSCs). ICCs derived from SHED were packed in immuno-isolatory biocompatible macro-capsules and transplanted into streptozotocin (STZ)-induced diabetic mice. Non-diabetic and diabetic controls were transplanted with macro-capsules with or without islets. RESULTS: SHED were superior to DPSCs. STZ diabetic mice alone and mice transplanted with empty macro-capsules exhibited hyperglycemia throughout the experiment, whereas mice transplanted with macro-capsules containing ICCs were restored to normoglycemia within 3-4 weeks, which persisted for >60 days. CONCLUSIONS: Our results demonstrate for the first time that ICCs derived from SHED reverse STZ diabetes in mice without immunosuppression and offer an autologous and non-controversial source of human tissue that could be used for stem cell therapy in diabetes.

Significance of soluble growth factors in the chondrogenic response of human umbilical cord matrix stem cells in a porous three dimensional scaffold.

Stem cell based tissue engineering has emerged as a promising strategy for articular cartilage regeneration. Foetal derived mesenchymal stem cells (MSCs) with their ease of availability, pluripotency and high expansion potential have been demonstrated to be an attractive cell source over adult MSCs. However, there is a need for optimisation of chondrogenic signals to direct the differentiation of these multipotent MSCs to chondrogenic lineage. In this study we have demonstrated the in vitro chondrogenesis of human umbilical cord matrix MSCs in three dimensional PVA-PCL (polyvinyl alcohol-polycaprolactone) scaffolds in the presence of the individual growth factors TGFß1, TGFß3, IGF, BMP2 and their combination with BMP2. Gene expression, histology and immunohistology were evaluated after 28 d culture. The induced cells showed the feature of chondrocytes in their morphology and expression of typical chondrogenic extracellular matrix molecules. Moreover, the real-time PCR assay has shown the expression of gene markers of chondrogenesis, SOX9, collagen type II and aggrecan. The expression of collagen type I and collagen type X was also evaluated. This study has demonstrated the successful chondrogenic induction of human umbilical cord MSCs in 3D scaffolds. Interestingly, the growth factor combination of TGF-ß3 and BMP-2 was found to be more effective for chondrogenesis as shown by the real-time PCR studies. The findings of this study suggest the importance of using growth factor combinations for successful chondrogenic differentiation of umbilical cord MSCs.

Growth and Regeneration of Osteochondral Cells in Bioactive Niche: A Promising Approach for Osteochondral Tissue Repair.

Functional repair of osteochondral defects caused due to osteoarthritis still remains the greatest challenge in orthopedic therapy. A prospective clinical strategy would be exploring osteochondral tissue engineering possibilities that promote simultaneous regeneration of the articular cartilage layer as well as the underlying subchondral bone. Incorporating the appropriate cues onto the scaffolds for the regeneration of the two contrasting tissues is therefore a demanding function. In the present study, a polymer-ceramic composite scaffolding material consisting of ternary bioactive glass (67.12 SiO2/28.5 CaO/4.38 P2O5 mol %) incorporated into a semi interpenetrating polymer network of hydrophilic-hydrophobic polymer (poly(vinyl alcohol)-polycaprolactone) matrix is prepared and physicochemically characterized. In vitro bioactivity, bone-bonding ability, and biocompatibility evaluation were performed in comparison with the pristine scaffold. The degree of chondrogenic and osteogenic potential of mesenchymal stem cells in both the scaffolds was evaluated by gene expression studies. Although both the scaffolds favored the differentiation to both cell lineages in their respective medium, a higher expression of bone specific genes found with the composite scaffold suggested that this composite scaffold would serve better for osteal layer and henceforth to promote the integration of the osteochondral construct at the defect site.

Three-dimensional wet electrospun scaffold system for the differentiation of adipose-derived mesenchymal stem cells to islet-like clusters.

Stem cell-derived islet-like clusters (ILCs) are an alternative source of pancreatic beta cells for the treatment of diabetic mellitus. An ideal 3D culture platform for the generation of ILCs of desired cluster size is a challenge due to the clustering of islet cells in the 2D culture systems. The islet cells cultured in 2D conditions produce clusters of large size, which are less efficient in terms of insulin secretion and viability. In this study, we report that ILCs formed on a PCL-based wet electrospun fibrous scaffold with larger pore size produced clusters of the desired size, compared to that cultured on a conventional electrospun sheet. The collagen functionalization on this wet electrospun polycaprolactone (PCL) scaffold showed enhanced insulin secretion and cell viability compared to the non-functionalized or conventionally electrospun PCL scaffold. The collagen-coated wet electrospun 3D scaffold produced ILCs of cluster diameter 70 ± 20 µm and the conventionally electrospun PCL sheet produced larger ILC clusters of diameter 300 ± 10 µm. Hence the results indicate the collagen-functionalized wet electrospun scaffold system could be a potential scaffold for islet tissue engineering.

Assessing the 3D Printability of an Elastomeric Poly(caprolactone-co-lactide) Copolymer as a Potential Material for 3D Printing Tracheal Scaffolds.

The advent of 3D printing technology has made remarkable progress in the field of tissue engineering. Yet, it has been challenging to reproduce the desired mechanical properties of certain tissues by 3D printing. This was majorly due to the lack of 3D printable materials possessing mechanical properties similar to the native tissue. In this study, we have synthesized four different ratios of poly(caprolactone-co-lactide (PLCL) and tested their 3D printing capabilities. The physicochemical properties of the material were characterized using Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Furthermore, the mechanical properties were assessed using the universal testing machine (UTM). The ratio with the higher lactide content was found to have better printability. Out of the different ratios assessed, a suitable ratio having the desired mechanical properties and printability was identified and 3D printed into a tracheal scaffold. Thus, PLCL can be a potential material for 3D printing of tissues like the trachea.

Human bone marrow-derived mesenchymal cells differentiate and mature into endocrine pancreatic lineage in vivo.

BACKGROUND AIMS: The scarcity of human islets for transplantation remains a major limitation of cell replacement therapy for diabetes. Bone marrow-derived progenitor cells are of interest because they can be isolated, expanded and offered for such therapy under autologous/allogeneic settings. METHODS: We characterized and compared human bone marrow-derived mesenchymal cells (hBMC) obtained from (second trimester), young (1-24 years) and adult (34-81 years) donors. We propose a novel protocol that involves assessment of paracrine factors from regenerating pancreas in differentiation and maturation of hBMC into endocrine pancreatic lineage in vivo. RESULTS: We observed that donor age was inversely related to growth potential of hBMC. Following in vitro expansion and exposure to specific growth factors involved in pancreatic development, hBMC migrated and formed islet-like cell aggregates (ICA). ICA show increased abundance of pancreatic transcription factors (Ngn3, Brn4, Nkx6.1, Pax6 and Isl1). Although efficient differentiation was not achieved in vitro, we observed significant maturation and secretion of human c-peptide (insulin) upon transplantation into pancreactomized and Streptozotocin (STZ)-induced diabetic mice. Transplanted ICA responded to glucose and maintained normoglycemia in diabetic mice. CONCLUSIONS: Our data demonstrate that hBMC have tremendous in vitro expansion potential and can be differentiated into multiple lineages, including the endocrine pancreatic lineage. Paracrine factors secreted from regenerating pancreas help in efficient differentiation and maturation of hBMC, possibly via recruiting chromatin modulators, to generate glucose-responsive insulin-secreting cells.

Retrieval of rat aortic smooth muscle cells as intact cell sheet for regenerative medicine: a cost effective approach using photo polymerization.

Cell-based therapeutics are promising routes for the regeneration of damaged cells and organs. The recovery of cells cultured in vitro for such applications requires the use of proteolytic enzymes which deteriorate its property by disruption of cell-cell and cell-matrix interactions. Intact cell sheets can be retrieved with the use of thermo responsive polymer grafted on to the culture plates. Our study presents the use of photo-polymerization as a simple and inexpensive way to create thermo-responsive culture surfaces for the detachment of intact cell sheet. Poly (N-isopropyl acrylamide) (PNIPAAm) was synthesized by photo-polymerization and characterized by NMR spectroscopy, differential scanning calorimetry and gel permeation chromatography. Thermo-responsive culture dishes were prepared by the coating method and characterized for its thermo-responsive efficacy using FTIR spectroscopy and water contact angle measurements. Atomic force microscopy depicted the thin coating achieved with this method is similar to the conventional grafting method. Suitability for cell culture and cell sheet retrieval was assessed by culturing rat aortic smooth muscle cells in the PNIPAAm coated tissue culture plates. The cells remained viable as evident from the live dead assay and the cell sheet was detached by low temperature treatment. The results demonstrate a versatile method for creating thermo responsive culture surfaces while eliminating the use of expensive radiation sources for the conventional grafting method.

Dual crosslinked pullulan-gelatin cryogel scaffold for chondrocyte-mediated cartilage repair: synthesis, characterization andin vitroevaluation.

Cryogels, a subset of hydrogels, have recently drawn attention for cartilage tissue engineering due to its inherent microporous architecture and good mechanical properties. In this study a dual crosslinked pullulan-gelatin cryogel (PDAG) scaffold was synthesized by crosslinking gelatin with oxidized pullulan by Schiff's base reaction followed by cryogelation. Chondrocytes seeded within the PDAG scaffolds and cultured for 21 din vitrodemonstrated enhanced cell proliferation, enhanced production of cartilage-specific extracellular matrix and up-regulated sulfated glycosaminoglycan without altering the articular chondrocyte phenotype. Quantitative reverse transcription-polymerase chain reaction-based gene expression studies, immunofluorescence, and histological studies demonstrated that the PDAG scaffold significantly enhanced the expression of chondrogenic marker genes such as type II collagen, aggrecan, and SOX9. Taken together, these results demonstrated that PDAG scaffold prepared by sequential Schiff's base reaction and cryogelation would be a promising cell-responsive scaffold for cartilage tissue engineering applications.

3D-printed biphasic scaffolds for the simultaneous regeneration of osteochondral tissues.

Osteochondral tissue engineering (OCTE) involves the simulation of highly complex tissues with disparate biomechanical properties. OCTE is regarded as the best option for treating osteochondral defects, most of the drawbacks of current treatment methodologies can be addressed by this method. In recent years, the conventional scaffolds used in cartilage and bone regeneration are gradually being replaced by 3D printed scaffolds (3DP). In the present study, we devised the strategy of 3D printing for fabricating biphasic and integrated scaffolds that are loaded with bioactive factors for enhancing the osteochondral tissue regeneration. Polycaprolactone (PCL) and poly(lactic-co-glycolic acid) (PLGA), is used along with bioactive factors (chondroitin sulphate and beta-tricalcium phosphate (ßTCP)) for the upper cartilage and lower bone layer respectively. The 3D printed bi-layered scaffolds with varying infill density, to mimic the native tissue, are not previously explored for OCTE. Hence, we tested the simultaneous osteochondrogenic differentiation inducing potential of the aforesaid 3D printed biphasic scaffoldsin vitro, using rabbit adipose derived mesenchymal stem cells (ADMSCs). Further, the biphasic scaffolds were highly cytocompatible, with excellent cell adhesion properties and cellular morphology. Most importantly, these biphasic scaffolds directed the simultaneous differentiation of a single stem cell population in to two cell lineages (simultaneous differentiation of rabbit ADMSCs into chondrocytes and osteoblasts). Further, these scaffolds enhanced the production of ECM and induced robust expression of marker genes that is specific for respective cartilage and bone layers. The 3D printed OCTE scaffold of our study hence can simulate the native osteochondral unit and could be potential futuristic biomimetic scaffold for osteochondral defects. Furtherin vivostudies are warranted.

Long-Term Evaluation of Allogenic Chondrocyte-Loaded PVA-PCL IPN Scaffolds for Articular Cartilage Repair in Rabbits.

OBJECTIVE: This study tested the long-term efficacy of two synthetic scaffolds for osteochondral defects and compare the outcomes with that of an established technique that uses monolayer cultured chondrocytes in a rabbit model. METHODS: Articular cartilage defect was created in both knees of 18 rabbits and divided into three groups of six in each. The defects in first group receiving cells loaded on Scaffold A (polyvinyl alcohol-polycaprolactone semi-interpenetrating polymer network (Monophasic, PVA-PCL semi-IPN), the second on Scaffold B (biphasic, PVA-PCL incorporated with bioglass as the lower layer), and the third group received chondrocytes alone. One animal from each group was sacrificed at 2 months and the rest at 1 year. O'Driscoll's score measured the quality of cartilage repair. RESULTS: The histological outcome had good scores (22, 20, and 19) for all three groups at 2 months. At 1-year follow-up, the chondrocyte alone group had the best scores (mean 20.0 ± 1.4), while the group treated by PVA-PCL semi-IPN scaffolds fared better (mean 15 ± 4.2) than the group that received biphasic scaffolds (mean 11.8 ± 5.9). In all three groups, defects treated without cells scored less than the transplant. CONCLUSION: These results indicate that while these scaffolds with chondrocytes perform well initially, their late outcome is disappointing. We propose that for all scaffold-based tissue repairs, a long-term evaluation should be mandatory. The slow degrading scaffolds need further modifications to improve the milieu for long-term growth of chondrocytes and their hyaline phenotype for the better incorporation of tissue-engineered constructs.

Generation of pancreatic hormone-expressing islet-like cell aggregates from murine adipose tissue-derived stem cells.

The success of cell replacement therapy for diabetes depends on the availability and generation of an adequate number of islets, preferably from an autologous origin. Stem cells are now being probed for the generation of physiologically competent, insulin-producing cells. In this investigation, we explored the potential of adipose tissue-derived stem cells (ASCs) to differentiate into pancreatic hormone-expressing islet-like cell aggregates (ICAs). We initiated ASC culture from epididymal fat pads of Swiss albino mice to obtain mesenchymal cells, murine epididymal (mE)-ASCs. Subsequent single-cell cloning resulted in a homogeneous cell population with a CD29(+)CD44(+)Sca-1(+) surface antigen expression profile. We formulated a 10-day differentiation protocol to generate insulin-expressing ICAs from mE-ASCs by progressively changing the differentiation cocktail on day 1, day 3, and day 5. Our stage-specific approach successfully differentiated mesodermic mE-ASCs into definitive endoderm (cells expressing Sox17, Foxa2, GATA-4, and cytokeratin [CK]-19), then into pancreatic endoderm (cells expressing pancreatic and duodenal homeobox [PDX]-1, Ngn3, NeuroD, Pax4, and glucose transporter 2), and finally into cells expressing pancreatic hormones (insulin, glucagon, somatostatin). Fluorescence-activated cell sorting analysis showed that day 5 ICAs contained 64.84% +/- 7.03% PDX-1(+) cells, and in day 10 mature ICAs, 48.17% +/- 3% of cells expressed C-peptide. Day 10 ICAs released C-peptide in a glucose-dependent manner, exhibiting in vitro functionality. Electron microscopy of day 10 ICAs revealed the presence of numerous secretory granules within the cell cytoplasm. Calcium alginate-encapsulated day 10 ICAs (1,000-1,200), when transplanted i.p. into streptozotocin-induced diabetic mice, restored normoglycemia within 2 weeks. The data presented here demonstrate the feasibility of using ASCs as a source of autologous stem cells to differentiate into the pancreatic lineage.

Reversal of experimental diabetes in mice by transplantation of neo-islets generated from human amnion-derived mesenchymal stromal cells using immuno-isolatory macrocapsules.

BACKGROUND AIMS: The ethical and biologic limitations with current sources of stem cells have resulted in a quest to look for alternative sources of multipotent stem cells of human origin. Amniotic membrane is of interest as a source of cells for regenerative medicine because of its ease of availability, plasticity and inexhaustible source that does not violate the sanctity of independent life. Although researchers have shown the stem cell-like potential of human amniotic epithelial cells, the mesenchymal part of amnion has remained less explored. METHODS: We established a long-term culture of mesenchymal-like stem cells derived from full-term human amniotic membrane and their differentiation into functional pancreatic lineage. RESULTS: The amnion-derived mesenchymal-like stem cells expressed various mesenchymal markers and demonstrated multilineage differentiation capacity. We also observed that these cells could form islet-like clusters (ILC) on exposure to serum-free defined media containing specific growth factor and differentiating agents. Differentiated ILC showed expression of human insulin, glucagon and somatostatin by immunocytochemistry, while quantitative reverse transcription/real-time-polymerase chain reaction (qRT-PCR) data demonstrated the expression of insulin, glucagon, somatostatin, Ngn3 and Isl1. Moreover, encapsulation of the ILC in polyurethane-polyvinyl pyrrolidone macrocapsules and their subsequent transplantation in experimental diabetic mice resulted in restoration of normoglycemia, indicating their ability to respond to high glucose without immunorejection. CONCLUSIONS: Our results demonstrate that amnion-derived mesenchymal stromal cells can undergo islet neogenesis, indicating amnion as an alternative source of islets for cell replacement therapy in diabetes.

Keratinocytes-hair follicle bulge stem cells-fibroblasts co-cultures on a tri-layer skin equivalent derived from gelatin/PEG methacrylate nanofibers.

Generation of full thickness skin equivalent models is of increasing interest in tissue engineering because of the limitations inherent to current models. In recent years, considerable interest has been given to electrospun hybrid nanofibers prepared using natural and synthetic combinations of polymers. By blending two polymers, gelatin and PEG methacrylate we created a novel functional hydrogel-named GelMet. By adjusting the concentration of GelMet between 14 and 20wt%, three types of electrospun membranes were fabricated. Keratinocytes, hair follicle bulge stem cells (HFBSCs) and fibroblasts were successfully isolated and cultured in 14 wt%, 17 wt% and 20 wt% GelMet scaffolds respectively and generated a tri-layered electrospun construct. Characterization of GelMet electrospun membranes were compared with those of the pure gelatin nanofibers. Due to plasticity, by incorporating HFBSCs, it is expected to increase the cell content of skin substitute without the need to incorporate several different cell populations. The fiber diameter and pore size of the scaffold for each layer were fabricated in such a way to mimic the structural gradation of collagen matrix across the native skin. Good mechanical properties and dimensional stability of GelMet scaffold, combined with the ability to support cell growth in vitro, suggest its tremendous potential application in skin tissue engineering.

Tissue-engineered islet-like cell clusters generated from adipose tissue-derived stem cells on three-dimensional electrospun scaffolds can reverse diabetes in an experimental rat model and the role of porosity of scaffolds on cluster differentiation.

In the current study, three-dimensional (3D) nanofibrous scaffolds with pore sizes in the range of 24-250 µm and 24-190 µm were fabricated via a two-step electrospinning method to overcome the limitation of obtaining three-dimensionality with large pore sizes for islet culture using conventional electrospinning. The scaffolds supported the growth and differentiation of adipose-derived mesenchymal stem cells to islet-like clusters (ILCs). The pore size of the scaffolds was found to influence the cluster size, viability and insulin release of the differentiated islets. Hence, islet clusters of the desired size could be developed for transplantation to overcome the loss of bigger islets due to hypoxia which adversely impacts the outcome of transplantation. The tissue-engineered constructs with ILC diameter of 50 µm reduced glycemic value within 3-4 weeks after implantation in the omental pouch of diabetic rats. Detection of insulin in the serum of implanted rats demonstrates that the tissue-engineered construct is efficient to control hyperglycemia. Our findings prove that the 3D architecture and pore size of scaffolds regulates the morphology and size of islets during differentiation which is critical in the survival and function of ILCs in vitro and in vivo.