Two Decades of Advances and Limitations in Organ Recellularization

The recellularization of tissues after decellularization is a relatively new technology in the field of tissue engineering (TE). Decellularization involves removing cells from a tissue or organ, leaving only the extracellular matrix (ECM). This can then be recellularized with new cells to create functional tissues or organs. The first significant mention of recellularization in decellularized tissues can be traced to research conducted in the early 2000s. One of the landmark studies in this field was published in 2008 by Ott, where researchers demonstrated the recellularization of a decellularized rat heart with cardiac cells, resulting in a functional organ capable of contraction. Since then, other important studies have been published. These studies paved the way for the widespread application of recellularization in TE, demonstrating the potential of decellularized ECM to serve as a scaffold for regenerating functional tissues. Thus, although the concept of recellularization was initially explored in previous decades, these studies from the 2000s marked a major turning point in the development and practical application of the technology for the recellularization of decellularized tissues. The article reviews the historical advances and limitations in organ recellularization in TE over the last two decades.

A hybrid construct of decellularized matrix and fibrin for differentiating adipose stem cells into insulin-producing cells, an optimized in vitro assessment

The generation of insulin-producing cells (IPCs) is an attractive approach for replacing damaged β cells in diabetic patients. In the present work, we introduced a hybrid platform of decellularized amniotic membrane (dAM) and fibrin encapsulation for differentiating adipose tissue-derived stem cells (ASCs) into IPCs. ASCs were isolated from healthy donors and characterized. Human AM was decellularized, and its morphology, DNA, collagen, glycosaminoglycan (GAG) contents, and biocompatibility were evaluated. ASCs were subjected to four IPC differentiation methods, and the most efficient method was selected for the experiment. ASCs were seeded onto dAM, alone or encapsulated in fibrin gel with various thrombin concentrations, and differentiated into IPCs according to a method applying serum-free media containing 2-mercaptoethanol, nicotinamide, and exendin-4. PDX-1, GLUT-2 and insulin expression were evaluated in differentiated cells using real-time PCR. Structural integrity and collagen and GAG contents of AM were preserved after decellularization, while DNA content was minimized. Cultivating ASCs on dAM augmented their attachment, proliferation, and viability and enhanced the expression of PDX-1, GLUT-2, and insulin in differentiated cells. Encapsulating ASCs in fibrin gel containing 2 mg/ml fibrinogen and 10 units/ml thrombin increased their differentiation into IPCs. dAM and fibrin gel synergistically enhanced the differentiation of ASCs into IPCs, which could be considered an appropriate strategy for replacing damaged β cells.

Differentiation of Wharton's Jelly-derived mesenchymal stem cells into insulin-producing beta cells with the enhanced functional level on electrospun PRP-PVP-PCL/PCL fiber scaffold

Diabetes is a global problem that threatens human health. Cell therapy methods using stem cells, and tissue engineering of pancreatic islets as new therapeutic approaches have increased the chances of successful diabetes treatment. In this study, to differentiate Wharton's Jelly-derived mesenchymal stem cells (WJ-MSCs) into insulin-producing cells (IPCs) with improved maturity, and function, platelet-rich plasma (PRP)-Polyvinylpyrrolidone (PVP)-Polycaprolactone (PCL)/PCL scaffold was designed. The two-dimensional (2D) control group included cell culture without differentiation medium, and the experimental groups included 2D, and three-dimensional (3D) groups with pancreatic beta cell differentiation medium. WJ-MSCs-derived IPCs on PRP-PVP-PCL/PCL scaffold took round cluster morphology, the typical pancreatic islets morphology. Real-time PCR, immunocytochemistry, and flowcytometry data showed a significant increase in pancreatic marker genes in WJ-MSCs-derived IPCs on the PRP-PVP-PCL/PCL scaffold compared to the 2D-experimental group. Also, using the ELISA assay, a significant increase in the secretion of insulin, and C-peptide was measured in the WJ-MSCs-derived IPCs of the 3D-experimental group compared to the 2D experimental group, the highest amount of insulin (38 µlU/ml), and C-peptide (43 pmol/l) secretion was in the 3D experimental group, and in response to 25 mM glucose solution, which indicated a significant improvement in the functional level of the WJ-MSCs-derived IPCs in the 3D group. The results showed that the PRP-PVP-PCL/PCL scaffold can provide an appropriate microenvironment for the engineering of pancreatic islets, and the generation of IPCs.

Decellularized tracheal scaffold as a promising 3D scaffold for tissue engineering applications

Tissue engineering is a science that uses the combination of scaffolds, cells, and active biomolecules to make tissue in order to restore or maintain its function and improve the damaged tissue or even an organ in the laboratory. The purpose of this research was to study the characteristics and biocompatibility of decellularized sheep tracheal scaffolds and also to investigate the differentiation of Adipose-derived stem cells (AD-MSCs) into tracheal cells. After the decellularization of sheep tracheas through the detergent-enzyme method, histological evaluations, measurement of biochemical factors, measurement of DNA amount, and photographing the ultrastructure of the samples by scanning electron microscopy (SEM), they were also evaluated mechanically. Further, In order to check the viability and adhesion of stem cells to the decellularized scaffolds, adipose mesenchymal stem cells were cultured on the scaffolds, and the 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay was performed. The expression analysis of the intended genes for the differentiation of mesenchymal stem cells into tracheal cells was evaluated by the real-time PCR method. These results show that the prepared scaffolds are an ideal model for engineering applications, have high biocompatibility, and that the tracheal scaffold provides a suitable environment for the differentiation of ADMSCs. This review provides a basis for future research on tracheal decellularization scaffolds, serves as a suitable model for organ regeneration, and paves the way for their use in clinical medicine.

Generation of glucose sensitive insulin-secreting cells from human induced pluripotent stem cells on optimized polyethersulfone hybrid nanofibrous scaffold

BACKGROUND

In the realm of diabetes treatment, various strategies have been tried, including islet transplantation and common drug therapies, but the limitations of these procedures and lack of responsive to the high number of patients have prompted researchers to develop a new method. In recent decades, the use of stem cells and three-dimonsional (3D) scaffold to produce insulin-secreting cells is one of the most promising new approaches. Meanwhile, human-induced pluripotent stem cells (iPSCs) propose due to advantages such as autologousness and high pluripotency in cell therapy. This study aimed to evaluate the differentiation of iPSCs into pancreatic islet insuli-producing cells (IPCs) on Silk/PES (polyethersulfone) nanofibers as a 3D scaffold and compare it with a two-dimonsional (2D) cultured group.

METHODS

Investigating the functional, morphological, molecular, and cellular characteristics of differentiated iPSCs on control cultures (without differentiation medium), 2D and 3D were measured by various methods such as electron microscopy, Q-PCR, immunofluorescence, western blot, and ELISA.

RESULTS

This investigation revealed that differentiated cells on the 3D Silk/PES scaffold expressed pancreatic specific-markers such as insulin and pdx1 at higher levels than the control and 2D groups, with a significant difference between the two groups. All results of Q-PCR, immunocytochemistry, and western blot showed that IPCs in the silk/PES 3D group was more efficient than in the 2D group. In the face of these cases, the release of insulin and C-peptide in response to several concentrations of glucose in the 3D group was significantly higher than in the 2D culture.

CONCLUSION

Finally, our findings displayed that optimized Silk/PES 3D scaffolds can enhance the differentiation of IPCs from iPSCs compared to the 2D culture group.

Repopulation of decellularized organ scaffolds with human pluripotent stem cell-derived pancreatic progenitor cells

Diabetes is an emerging global epidemic that affects more that 285 million people worldwide. Engineering of endocrine pancreas tissue holds great promise for the future of diabetes therapy. Here we demonstrate the feasibility of re-engineering decellularized organ scaffolds using regenerative cell source. We differentiated human pluripotent stem cells (hPSC) toward pancreatic progenitor (PP) lineage and repopulated decellularized organ scaffolds with these hPSC-PP cells. We observed that hPSCs cultured and differentiated as aggregates are more suitable for organ repopulation than isolated single cell suspension. However, recellularization with hPSC-PP aggregates require a more extensive vascular support, which was found to be superior in decellularized liver over the decellularized pancreas scaffolds. Upon continued culture for nine days with chemical induction in the bioreactor, the seeded hPSC-PP aggregates demonstrated extensive and uniform cellular repopulation and viability throughout the thickness of the liver scaffolds. Furthermore, the decellularized liver scaffolds was supportive of the endocrine cell fate of the engrafted cells. Our novel strategy to engineer endocrine pancreas construct is expected to find potential applications in preclinical testing, drug discovery and diabetes therapy.

Tissue engineering of decellularized pancreas scaffolds for regenerative medicine in diabetes

Diabetes mellitus is a global disease requiring long-term treatment and monitoring. At present, pancreas or islet transplantation is the only reliable treatment for achieving stable euglycemia in Type I diabetes patients. However, the shortage of viable pancreata for transplantation limits the use of this therapy for the majority of patients. Organ decellularization and recellularization is emerging as a promising solution to overcome the shortage of viable organs for transplantation by providing a potential alternative source of donor organs. Several studies on decellularization and recellularization of rodent, porcine, and human pancreata have been performed, and show promise for generating usable decellularized pancreas scaffolds for subsequent recellularization and transplantation. In this state-of-the-art review, we provide an overview of the latest advances in pancreas decellularization, recellularization, and revascularization. We also discuss clinical considerations such as potential transplantation sites, donor source, and immune considerations. We conclude with an outlook on the remaining work that needs to be done in order to realize the goal of using this technology to create bioengineered pancreata for transplantation in diabetes patients. STATEMENT OF SIGNIFICANCE: Pancreas or islet transplantation is a means of providing insulin-independence in diabetes patients. However, due to the shortage of viable pancreata, whole-organ decellularization and recellularization is emerging as a promising solution to overcome organ shortage for transplantation. Several studies on decellularization and recellularization of rodent, porcine, and human pancreata have shown promise for generating usable decellularized pancreas scaffolds for subsequent recellularization and transplantation. In this state-of-the-art review, we highlight the latest advances in pancreas decellularization, recellularization, and revascularization. We also discuss clinical considerations such as potential transplantation sites, donor source, and immune considerations. We conclude with future work that needs to be done in order to realize clinical translation of bioengineered pancreata for transplantation in diabetes patients.

Tissue engineering approaches and generation of insulin-producing cells to treat type 1 diabetes

Tissue engineering (TE) has become a new effective solution to a variety of medical problems, including diabetes. Mesenchymal stem cells (MSCs), which have the ability to differentiate into endodermal and mesodermal cells, appear to be appropriate for this function. The purpose of this review was to evaluate the outcomes of various researches on the insulin-producing cells (IPCs) generation from MSCs with TE approaches to increase efficacy of type 1 diabetes treatments. The search was performed in PubMed/Medline, Scopus and Embase databases until 2021. Studies revealed that MSCs could also differentiate into IPCs under certain conditions. Therefore, a wide range of protocols have been used for this differentiation, but their effectiveness is very different. Scaffolds can provide a microenvironment that enhances the MSCs to IPCs differentiation, improves their metabolic activity and up-regulate pancreatic-specific transcription factors. They also preserve IPCs architecture and enhance insulin production as well as protect against cell death. This systematic review offers a framework for prospective research based on data. In vitro and in vivo evidence suggests that scaffold-based TE can improve the viability and function of IPCs.

Biofabrication, biochemical profiling, and in vitro applications of salivary gland decellularized matrices via magnetic bioassembly platforms

Trending three-dimensional tissue engineering platforms developed via biofabrication and bioprinting of exocrine glands are on the rise due to a commitment to organogenesis principles. Nevertheless, a proper extracellular matrix (ECM) microarchitecture to harbor primary cells is yet to be established towards human salivary gland (SG) organogenesis. By using porcine submandibular gland (SMG) biopsies as a proof-of-concept to mimic the human SG, a new decellularized ECM bioassembly platform was developed herein with varying perfusions of sodium dodecyl sulfate (SDS) to limit denaturing events and ensure proper preservation of the native ECM biochemical niche. Porcine SMG biopsies were perfused with 0.01%, 0.1%, and 1% SDS and bio-assembled magnetically in porous polycarbonate track-etched (PCTE) membrane. Double-stranded DNA (dsDNA), cell removal efficiency, and ECM biochemical contents were analyzed. SDS at 0.1% and 1% efficiently removed dsDNA (< 50 ng/mg) and preserved key matrix components (sulfated glycosaminoglycans, collagens, elastin) and the microarchitecture of native SMG ECM. Bio-assembled SMG decellularized ECM (dECM) perfused with 0.1-1% SDS enhanced cell viability, proliferation, expansion confluency rates, and tethering of primary SMG cells during 7 culture days. Perfusion with 1% SDS promoted greater cell proliferation rates while 0.1% SDS supported higher acinar epithelial expression when compared to basement membrane extract and other substrates. Thus, this dECM magnetic bioassembly strategy was effective for decellularization while retaining the original ECM biochemical niche and promoting SMG cell proliferation, expansion, differentiation, and tethering. Altogether, these outcomes pave the way towards the recellularization of this novel SMG dECM in future in vitro and in vivo applications.

Establishment of decellularized extracellular matrix scaffold derived from caprine pancreas as a novel alternative template over porcine pancreatic scaffold for prospective biomedical application

In this study, the caprine pancreas has been presented as an alternative to the porcine organ for pancreatic xenotransplantation with lesser risk factors. The obtained caprine pancreas underwent a systematic cycle of detergent perfusion for decellularization. It was perfused using anionic (0.5% w/v sodium dodecyl sulfate) as well as non-ionic (0.1% v/v triton X-100, t-octyl phenoxy polyethoxy ethanol) detergents and washed intermittently with 1XPBS supplemented with 0.1% v/v antibiotic and nucleases in a gravitation-driven set-up. After 48 h, a white decellularized pancreas was obtained, and its extracellular matrix (ECM) content was examined for scaffold-like properties. The ECM content was assessed for removal of cellular content, and nuclear material was evaluated with temporal H&E staining. Quantified DNA was found to be present in a negligible amount in the resultant decellularized pancreas tissue (DPT), thus prohibiting it from triggering any immunogenicity. Collagen and fibronectin were confirmed to be preserved upon trichrome and immunohistochemical staining, respectively. SEM and AFM images reveal interconnected collagen fibril networks in the DPT, confirming that collagen was unaffected. sGAG was visualized using Prussian blue staining and quantified with DMMB assay, where DPT has effectively retained this ECM component. Uniaxial tensile analysis revealed that DPT possesses better elasticity than NPT (native pancreatic tissue). Physical parameters like tensile strength, stiffness, biodegradation, and swelling index were retained in the DPT with negligible loss. The cytocompatibility analysis of DPT has shown no cytotoxic effect for up to 72 h on normal insulin-producing cells (MIN-6) and cancerous glioblastoma (LN229) cells in vitro. The scaffold was recellularized using isolated mouse islets, which have established in vitro cell proliferation for up to 9 days. The scaffold received at the end of the decellularization cycle was found to be non-toxic to the cells, retained biological and physical properties of the native ECM, suitable for recellularization, and can be used as a safer and better alternative as a transplantable organ from a xenogeneic source.

Bioengineering the Vascularized Endocrine Pancreas: A Fine-Tuned Interplay Between Vascularization, Extracellular-Matrix-Based Scaffold Architecture, and Insulin-Producing Cells

Intrahepatic islet transplantation is a promising β-cell replacement strategy for the treatment of type 1 diabetes. Instant blood-mediated inflammatory reactions, acute inflammatory storm, and graft revascularization delay limit islet engraftment in the peri-transplant phase, hampering the success rate of the procedure. Growing evidence has demonstrated that islet engraftment efficiency may take advantage of several bioengineering approaches aimed to recreate both vascular and endocrine compartments either ex vivo or in vivo. To this end, endocrine pancreas bioengineering is an emerging field in β-cell replacement, which might provide endocrine cells with all the building blocks (vascularization, ECM composition, or micro/macro-architecture) useful for their successful engraftment and function in vivo. Studies on reshaping either the endocrine cellular composition or the islet microenvironment have been largely performed, focusing on a single building block element, without, however, grasping that their synergistic effect is indispensable for correct endocrine function. Herein, the review focuses on the minimum building blocks that an ideal vascularized endocrine scaffold should have to resemble the endocrine niche architecture, composition, and function to foster functional connections between the vascular and endocrine compartments. Additionally, this review highlights the possibility of designing bioengineered scaffolds integrating alternative endocrine sources to overcome donor organ shortages and the possibility of combining novel immune-preserving strategies for long-term graft function.

Recent advancements in decellularized matrix technology for bone tissue engineering

The native extracellular matrix (ECM) provides a matrix to hold tissue/organ, defines the cellular fate and function, and retains growth factors. Such a matrix is considered as a most biomimetic scaffold for tissue engineering due to the biochemical and biological components, 3D hierarchical structure, and physicomechanical properties. Several attempts have been performed to decellularize allo- or xeno-graft tissues and used them for bone repairing and regeneration. Decellularized ECM (dECM) technology has been developed to create an in vivo-like microenvironment to promote cell adhesion, growth, and differentiation for tissue repair and regeneration. Decellularization is mediated through physical, chemical, and enzymatic methods. In this review, we describe the recent progress in bone decellularization and their applications as a scaffold, hydrogel, bioink, or particles in bone tissue engineering. Furthermore, we address the native dECM limitations and the potential of non-bone dECM, cell-based ECM, and engineered ECM (eECM) for in vitro osteogenic differentiation and in vivo bone regeneration.

Application of iPSCs derived pancreatic β-like cells using pancreatic bio-scaffold

This study aimed toengineer a pancreatic tissue. Intact rat pancreases were successfully decellularized, and were reseeded with human-induced pluripotent stem cells using different 2D and 3D culture growth factors. The differentiation process was assessed for the presence of a pancreas-like tissue. The histology and SEM analysis revealed cell attachment in all samples, except for the Exp4, and the Flow-cytometry provided 87% viability for the differentiated cells. In Exp1, PDX1 with the positive expression of 2.87±0.06 was dramatically higher than Exp2 with a 2.44±0.06 reaction. NGN3-reactions were 8±0.1 and 6.6±0.2 in Exp1 and Exp2 at P < 0.05, respectively. C-peptide with the expression of 7.5±0.7 in Exp3 was almost equal to that in Exp1 and Exp2. Glucagon (5.1±1) and PDX1 (3.2±0.82) in Exp3 indicated no significant difference. The significant upregulations of pancreatic endocrine markers (PDX1 and NGN3), and the cell-specific glucose transporter (GLUT2) were observed in the differentiated IPCs in the 3D culture of Exp2 after 21 days. The highest insulin and C-peptide concentrations were observed in Exp2. In Exp3, insulin secretion in response to high glucose and 10 mM arginine was 42.43 ±6.34 μU/ml. A decellularized pancreas in the presence of hiPSCs and growth factors could be efficiently used as a natural scaffold.

Decellularized Matrix Bioscaffolds: Implementation of Native Microenvironment in Pancreatic Tissue Engineering

ABSTRACT

Type 1 diabetes is an autoimmune disease, and its incidence is usually estimated in the range of 5% to 10%. Currently, the administration of exogenous insulin is the standard of care therapy. However, this therapy is not effective in some patients who may develop some chronic complications. Islet transplantation into the liver is another therapy with promising outcomes; however, the long-term efficacy of this therapeutic option is limited to a small number of patients. Because native extracellular matrix (ECM) components provide a suitable microenvironment for islet functions, engineering a 3-dimensional construct that recapitulates the native pancreatic environment could address these obstacles. Many attempts have been conducted to mimic an in vivo microenvironment to increase the survival of islets or islet-like clusters. With the advent of decellularization technology, it is possible to use a native ECM in organ engineering. Pancreatic decellularized bioscaffold provides proper cell-cell and cell-ECM interactions and retains growth factors that are critical in the determination of cell fate within a native organ. This review summarizes the current knowledge of decellularized matrix technology and addresses its possible limitations before use in the clinic.

Histological and biochemical investigation of the renoprotective effects of metformin in diabetic and prostate cancer model

BACKGROUND

Diabetes and cancer have common physiological and biochemical mechanisms. Metformin is the preferred drug of choice for the treatment of diabetes. Prostate cancer can be modeled in by injection of MAT-Lylu cells. A model of diabetes in rats is induced by streptozotocin injectıon. In the current study, we explored the mechanisms by which diabetes accelerates cancer, and evaluated the effects of metformin to know whether it has any impact against the damage caused by cancer and diabetic + cancer via histopathological and biochemical parameters of kidney tissue.

METHODS

The experiment was carried out in rats. Groups 1-Control, 2- Diabetic, 3-Cancer, 4-Diabetic + cancer, 5-Diabetic + cancer + metformin, 6-Cancer + metformin. Metformin treatment was applied by gavage every day. The research ended on the 14th day. The collected kidney tissue sections were stained with Hematoxylin-Eosin.

RESULTS

Histological evaluation showed moderate to severe damage to the kidney tissue following diabetic and cancer processess. In diabetic, cancer and diabetic + cancer groups, reduced glutathione levels, total antioxidant status, sodium/potassium-ATPase and paraoxonase1 activities were found to be significantly abated. While advanced oxidized protein products, lipid peroxidation, nitric oxide, tumor necrosis factor-alpha, reactive oxygen species levels, total oxidant status, catalase, superoxide dismutase, glutathione-related antioxidant enzymes, myeloperoxidase, and arginase activities were significantly raised. The administration of metformin reversed these defects. The outcome of the reveals that histopathological and biochemical damage in cancer and diabetes + cancer groups decreased in the groups that received metformin.

CONCLUSION

In conclusion, metformin treatment can be considered an adjuvant candidate for kidney tissue in diabetes, prostate cancer and cancer therapy related damage.

Detection of the residual concentration of sodium dodecyl sulfate in the decellularized whole rabbit kidney extracellular matrix

To optimize rabbit kidney decellularization protocol, using sodium dodecyl sulfate (SDS) as a commonly used detergent, a methylene blue based assay was employed for detecting the minimum nontoxic SDS level for future cell seeding. The rabbit kidney tissues were decellularized with the perfusion-based method and underwent several investigations to determine the efficacy of decellularization in preserving the extracellular matrix (ECM) and cell removal. SDS detection was performed by incubating with methylene blue and subsequent extraction with chloroform. MTT (3-(4, 5-dimethylthiazol-2-yr)-2,5-diphenyltetrazolium bromide) assay and SDS release were also evaluated during the entire process. After the first washing cycle, SDS concentration was 0.036, in 500 mL of the washing liquid, which slowly decreased and reached to 0.009 % after at the end of seventh washing cycle. In the 9th cycle, SDS was gradually decreased and reached to 0.003 %. SDS was significantly released after one week of incubation which ceased after ten washing cycles. The results of MTT assay demonstrated that different cells exhibited various sensitivity levels when exposed to serial concentrations of SDS. Human embryonic kidney cells (HEK293) with 0.003 % threshold for cellular toxicity and 87.4 % cell viability were more resistant compared with mesenchymal stem cells with 0.001 % threshold and 85.4 % cell viability. Colorimetric assay with methylene blue is a straightforward and non-invasive method to detect residual SDS present in tissue and can also prevent ECM destruction after several washings for detergent removal from decellularized tissues.

Whole Organ Engineering: Approaches, Challenges, and Future Directions

End-stage organ failure remains a leading cause of morbidity and mortality across the globe. The only curative treatment option currently available for patients diagnosed with end-stage organ failure is organ transplantation. However, due to a critical shortage of organs, only a fraction of these patients are able to receive a viable organ transplantation. Those patients fortunate enough to receive a transplant must then be subjected to a lifelong regimen of immunosuppressant drugs. The concept of whole organ engineering offers a promising alternative to organ transplantation that overcomes these limitations. Organ engineering is a discipline that merges developmental biology, anatomy, physiology, and cellular interactions with enabling technologies such as advanced biomaterials and biofabrication to create bioartificial organs that recapitulate native organs in vivo. There have been numerous developments in bioengineering of whole organs over the past two decades. Key technological advancements include (1) methods of whole organ decellularization and recellularization, (2) three-dimensional bioprinting, (3) advanced stem cell technologies, and (4) the ability to genetically modify tissues and cells. These advancements give hope that organ engineering will become a commercial reality in the next decade. In this review article, we describe the foundational principles of whole organ engineering, discuss key technological advances, and provide an overview of current limitations and future directions.

Insulin production from hiPSC-derived pancreatic cells in a novel wicking matrix bioreactor

Clinical use of pancreatic β islets for regenerative medicine applications requires mass production of functional cells. Current technologies are insufficient for large-scale production in a cost-efficient manner. Here, we evaluate advantages of a porous cellulose scaffold and demonstrate scale-up to a wicking matrix bioreactor as a platform for culture of human endocrine cells. Scaffold modifications were evaluated in a multiwell platform to find the optimum surface condition for pancreatic cell expansion followed by bioreactor culture to confirm suitability. Preceding scale-up, cell morphology, viability, and proliferation of primary pancreatic cells were evaluated. Two optimal surface modifications were chosen and evaluated further for insulin secretion, cell morphology, and viable cell density for human-induced pluripotent stem cell-derived pancreatic cells at different stages of differentiation. Scale-up was accomplished with uncoated, amine-modified cellulose in a miniature bioreactor, and insulin secretion and cell metabolic profiles were determined for 13 days. We achieved 10-fold cell expansion in the bioreactor along with a significant increase in insulin secretion compared with cultures on tissue culture plastic. Our findings define a new method for expansion of pancreatic cells a on wicking matrix cellulose platform to advance cell therapy biomanufacturing for diabetes.

Preparation and characterization of human size whole heart for organ engineering: scaffold microangiographic imaging

Definitive treatment for end-stage heart failure is heart transplantation, however, this is associated with several limitations. Aim: We decellularized and assessed ovine hearts through coronary perfusion. To evaluate in situ recellularization, a decellular graft was transplanted hetrotopically into the omental wrap. Results: Cell removal was confirmed by DNA count (11.68 ± 3.42 ng/mg dry weight). Elastic, reticular and collagen fiber were well preserved. There was a slight change in both glycosaminoglycan (7.01 ± 1.36 to 8.37 ± 0.32 μg/mg) and collagen (32.37 ± 2.3 to 36.31 ± 2.1) μg/mg (p > 0.05). Angiography and blood circulation revealed an intact vascular network. Implantation led to proper vascularization. Image J indicated CD31: 23.98 ± 12.3; CD34: 48.67 ± 19.5 and αSMA: 78.33 ± 27.8 inch/cm. Conclusion: Bio-scaffold of human size heart is achievable for future steps employing this technique.

ECM in Differentiation: A Review of Matrix Structure, Composition and Mechanical Properties

Stem cell regenerative potential owing to the capacity to self-renew as well as differentiate into other cell types is a promising avenue in regenerative medicine. Stem cell niche not only provides physical scaffolding but also possess instructional capacity as it provides a milieu of biophysical and biochemical cues. Extracellular matrix (ECM) has been identified as a major dictator of stem cell lineage, thus understanding the structure of in vivo ECM pertaining to specific tissue differentiation will aid in devising in vitro strategies to improve the differentiation efficiency. In this review, we summarize details about the native architecture, composition and mechanical properties of in vivo ECM of the early embryonic stages and the later adult stages. Native ECM from adult tissues categorized on their origin from respective germ layers are discussed while engineering techniques employed to facilitate differentiation of stem cells into particular lineages are noted. Overall, we emphasize that in vitro strategies need to integrate tissue specific ECM biophysical cues for developing accurate artificial environments for optimizing stem cell differentiation.

Generation of Human Stem Cell-Derived Pancreatic Organoids (POs) for Regenerative Medicine

Insulin-dependent diabetes mellitus or type 1 diabetes mellitus (T1DM) is an auto-immune condition characterized by the loss of pancreatic β-cells. The curative approach for highly selected patients is the pancreas or the pancreatic islet transplantation. Nevertheless, these options are limited by a growing shortage of donor organs and by the requirement of immunosuppression.Xenotransplantation of porcine islets has been extensively investigated. Nevertheless, the strong xenoimmunity and the risk of transmission of porcine endogenous retroviruses, have limited their application in clinic. Generation of β-like cells from stem cells is one of the most promising strategies in regenerative medicine. Embryonic, and more recently, adult stem cells are currently the most promising cell sources exploited to generate functional β-cells in vitro. A number of studies demonstrated that stem cells could generate functional pancreatic organoids (POs), able to restore normoglycemia when implanted in different preclinical diabetic models. Nevertheless, a gradual loss of function and cell dead are commonly detected when POs are transplanted in immunocompetent animals. So far, the main issue to be solved is the post-transplanted islet loss, due to the host immune attack. To avoid this hurdle, nanotechnology has provided a number of polymers currently under investigation for islet micro and macro-encapsulation. These new approaches, besides conferring PO immune protection, are able to supply oxygen and nutrients and to preserve PO morphology and long-term viability.Herein, we summarize the current knowledge on bioengineered POs and the stem cell differentiation platforms. We also discuss the in vitro strategies used to generate functional POs, and the protocols currently used to confer immune-protection against the host immune attack (micro- and macro-encapsulation). In addition, the most relevant ongoing clinical trials, and the most relevant hurdles met to move towards clinical application are revised.