Acellular Extracellular Matrix Research Articles

Experimental studies on the repair and restitution of cartilage cartilage by cartilage acellular extracellular matrix and adipose tissue-derived stem cells

Experimental studies on the repair and restitution of cartilage cartilage by cartilage acellular extracellular matrix and adipose tissue-derived stem cells

Decellularization of the Porcine Ear Generates a Biocompatible, Nonimmunogenic Extracellular Matrix Platform for Face Subunit Bioengineering.

The purpose of this study was to assess whether perfusion-decellularization technology could be applied to facial grafts. Facial allotransplantation remains an experimental procedure. Regenerative medicine techniques allow fabrication of transplantable organs from an individual's own cells, which are seeded into extracellular matrix (ECM) scaffolds from animal or human organs. Therefore, we hypothesized that ECM scaffolds also can be created from facial subunits. We explored the use of the porcine ear as a clinically relevant face subunit model to develop regenerative medicine-related platforms for facial bioengineering. Porcine ear grafts were decellularized and histologic, immunologic, and cell culture studies done to determine whether scaffolds retained their 3D framework and molecular content; were biocompatible in vitro and in vivo, and triggered an anti-MHC immune response from the host. The cellular compartment of the porcine ear was completely removed except for a few cartilaginous cells, leaving behind an acellular ECM scaffold; this scaffold retained its complex 3D architecture and biochemical components. The framework of the vascular tree was intact at all hierarchical levels and sustained a physiologically relevant blood pressure when implanted in vivo. Scaffolds were biocompatible in vitro and in vivo, and elicited no MHC immune response from the host. Cells from different types remained viable and could even differentiate at the scale of a whole-ear scaffold. Acellular scaffolds were produced from the porcine ear, and may be a valuable platform to treat facial deformities using regenerative medicine approaches.

The rat pancreatic body tail as a source of a novel extracellular matrix scaffold for endocrine pancreas bioengineering

BackgroundRegenerative medicine and tissue engineering are promising approaches for organ transplantation. Extracellular matrix (ECM) based scaffolds obtained through the decellularization of natural organs have become the preferred platform for organ bioengineering. In the field of pancreas bioengineering, acellular scaffolds from different animals approximate the biochemical, spatial and vascular relationships of the native extracellular matrix and have been proven to be a good platform for recellularization and in vitro culture. However, artificial endocrine pancreases based on these whole pancreatic scaffolds have a critical flaw, specifically their difficult in vivo transplantation, and connecting their vessels to the recipient is a major limitation in the development of pancreatic tissue engineering. In this study, we focus on preparing a novel acellular extracellular matrix scaffold derived from the rat pancreatic body tail (pan-body-tail ECM scaffold).ResultsSeveral analyses confirmed that our protocol effectively removes cellular material while preserving ECM proteins and the native vascular tree. DNA quantification demonstrated an obvious reduction of DNA compared with that of the natural organ (from 931.9 ± 267.8 to 11.7 ± 3.6 ng/mg, P < 0.001); the retention of the sGAG in the decellularized pancreas (0.878 ± 0.37) showed no significant difference from the natural pancreas (0.819 ± 0.1) (P > 0.05). After transplanted with the recellularized pancreas, fasting glucose levels declined to 9.08 ± 2.4 mmol/l within 2 h of the operation, and 8 h later, they had decreased to 4.7 ± 1.8 mmol/l (P < 0.05).ConclusionsThe current study describes a novel pancreatic ECM scaffold prepared from the rat pancreatic body tail via perfusion through the left gastric artery. We further showed the pioneering possibility of in vivo circulation-connected transplantation of a recellularized pancreas based on this novel scaffold. By providing such a promising pancreatic ECM scaffold, the present study might represent a key improvement and have a positive impact on endocrine pancreas bioengineering.

Design and fabrication of injectable microcarriers composed of acellular cartilage matrix and chitosan

Cartilage is an avascular tissue with limited self-repair ability. Since the methods for treatment of cartilage defects have not been effective, new therapies based on tissue engineering are considered over the recent years. In this study, human cartilage tissue was decellularized and porous injectable microcarriers (MCs) composed of acellular extracellular matrix (ECM) of cartilage tissue and chitosan (CS), with different ECM weight ratios, were fabricated by electrospraying technique to be used in the treatment of articular cartilage defects. Various properties of ECM/CS MCs such as microstructure, mechanical strength, water uptake behaviour, and biodegradability rate were investigated. MCs with 1% ECM and 2% CS show appropriate characteristics in terms of pore size, density, porosity, and mechanical properties. MTT cytotoxicity assays performed on chondrocyte cells cultured on ECM/CS MCs with various amounts of ECM showed that the sample with 1% ECM content had the greatest cell attachment. Overall, it can be concluded that the prepared MCs with 1% ECM could be a potential candidate to be used in cartilage tissue engineering applications.

Mid-term function and remodeling potential of tissue engineered tricuspid valve: Histology and biomechanics

ObjectiveTricuspid valve reconstruction using a small intestinal submucosal porcine extracellular matrix (ECM) tube graft is hypothesized to be durable for six months and show signs of recellularization and growth potential. The purpose was to histologically and biomechanically test ECM valves before and after six months of implantation in pigs for comparison with native valves. MethodsTen 60 kg pigs were included, which survived tricuspid valve tube graft insertion. Anterior and septal tricuspid leaflets were explanted from all animals surviving more than one month and examined histologically (n = 9). Endothelialization, collagen content, mineralization, neovascularization, burst strength and tensile strength were determined for native valves (n = 5), ECM before implantation (n = 5), and ECM after six months (n = 5). ResultsCollagen density was significantly larger in ECM at implantation (baseline) compared to native leaflet tissue (0.3 ± 0.02 mg/mm3 vs. 0.1 ± 0.03 mg/mm3, p < .0001), but collagen density decreased and reached native leaflet collagen content, six months after ECM implantation (native vs. ECM valve at six months: 0.1 ± 0.03 mg/mm3 vs. 0.2 ± 0.05 mg/mm3, p = .8).Histologically, ECM valves showed endothelialization, host cell infiltration and structural collagen organization together with elastin generation after six months, indicating tissue remodeling and -engineering together with gradual development of a close-to-native leaflet structure without foreign body response. ConclusionsECM tricuspid tube grafts were stronger than native leaflet tissue. Histologically, the acellular ECM tube grafts showed evidence of constructive tissue remodeling with endothelialization and connective tissue organization. These findings support the concept of tissue engineering and recellularization, which are prerequisites for growth.

Processing of Human Cardiac Tissue Toward Extracellular Matrix Self-assembling Hydrogel for In Vitro and In Vivo Applications.

Acellular extracellular matrix preparations are useful for studying cell-matrix interactions and facilitate regenerative cell therapy applications. Several commercial extracellular matrix products are available as hydrogels or membranes, but these do not possess tissue-specific biological activity. Because perfusion decellularization is usually not possible with human heart tissue, we developed a 3-step immersion decellularization process. Human myocardial slices procured during surgery are first treated with detergent-free hyperosmolar lysis buffer, followed by incubation with the ionic detergent, sodium dodecyl sulfate, and the process is completed by exploiting the intrinsic DNase activity of fetal bovine serum. This technique results in cell-free sheets of cardiac extracellular matrix with largely preserved fibrous tissue architecture and biopolymer composition, which were shown to provide specific environmental cues to cardiac cell populations and pluripotent stem cells. Cardiac extracellular matrix sheets can then be further processed into a microparticle powder without further chemical modification, or, via short-term pepsin digestion, into a self-assembling cardiac extracellular matrix hydrogel with preserved bioactivity.

Preparation and characterization of acellular adipose tissue matrix using a combination of physical and chemical treatments.

Decellularized adipose extracellular matrix (ECM) has been used in the clinic to support the regeneration of adipose tissues. The methods used to produce adipose tissue ECM scaffolds exhibit distinct effects upon the structural and functional components of the resultant scaffold material. The current study presents an acellular ECM scaffold from human adipose tissues derived using successive physical and chemical treatments, including repeated freeze-thaw cycles followed by centrifugation, polar solvent extraction and enzymatic digestion. Cellular components, including nucleic acids were effectively removed without significant disruption of the morphology or structure of the ECM. The compositions of major ECM components were evaluated, including acid/pepsin soluble collagen, sulfated glycosaminoglycan and laminin. The decellularized ECM exhibited satisfactory mechanical properties. Cell seeding experiments involving human adipose-derived stem cells indicated that the decellularized ECM provided an inductive microenvironment for adipogenesis without the need for exogenous differentiation factors. Higher levels of glycerol-3-phosphate dehydrogenase activity were observed among induced cells in the ECM scaffolds when compared with induced cells in collagen type I scaffolds. In conclusion, the results suggested that the decellularized ECM, containing biological and chemical cues of native human ECM, may be an ideal scaffold material for autologous and allograft tissue engineering.

A Standardized Dissection Protocol to Generate Aortic Valvular Scaffolds from Porcine Hearts.

To describe a particular harvesting procedure for isolating intact porcine aortic heart valve roots as potential sources for biologic scaffolds. Fresh porcine hearts were brought to the Tissue Engineering and Regenerative Medicine Laboratory at the University of Medicine and Pharmacy in Targu Mures. The aortic roots were extracted from the porcine hearts by anatomical dissection. For this purpose, we used a basic surgical instrument kit. This initial phase was the first step in obtaining acellular extracellular matrix as a biologic scaffold material. Aortic roots were isolated with preservation of the ascending aorta as well as the intact aortic sinus and coronaries together with the adjacent myocardial tissue and anterior leaflet of the mitral valve. This approach allowed for safe mounting of roots into mounting rings for perfusion decellularization. The described procedure is a feasible protocol for obtaining intact biological valvular scaffolds from porcine hearts. Reduced requirements regarding tools and personnel underline the easiness of aortic root harvesting using this particular procedure.

Bioactive Extracellular Matrix Scaffold Promotes Adaptive Cardiac Remodeling and Repair

Structural cardiac remodeling after ischemic injury can induce a transition to heart failure from progressive loss of cardiac function. Cellular regenerative therapies are promising but face significant translational hurdles. Tissue extracellular matrix (ECM) holds the necessary environmental cues to stimulate cell-based endogenous myocardial repair pathways and promote adaptive remodeling toward functional recovery. Heart epicardium has emerged as an important anatomic niche for endogenous repair pathways including vasculogenesis and cardiogenesis. We show that acellular ECM scaffolds surgically implanted on the epicardium following myocardial infarction (MI) can attenuate structural cardiac remodeling and improve functional recovery. We assessed the efficacy of this strategy on post-MI functional recovery by comparing intact bioactive scaffolds with biologically inactivated ECM scaffolds. We confirm that bioactive properties within the acellular ECM biomaterial are essential for the observed functional benefits. We show that interaction of human cardiac fibroblasts with bioactive ECM can induce a robust cell-mediated vasculogenic paracrine response capable of functional blood vessel assembly. Fibroblast growth factor-2 is uncovered as a critical regulator of this novel bioinductive effect. Acellular bioactive ECM scaffolds surgically implanted on the epicardium post-MI can reprogram resident fibroblasts and stimulate adaptive pro-reparative pathways enhancing functional recovery. We introduce a novel surgical strategy fortissue repair that can be performed as an adjunct to conventional surgical revascularization with minimaltranslational challenges.

Optimization of Human Myocardium Decellularization Method for the Construction of Implantable Patches.

Cardiac tissue engineering by means of synthetic or natural scaffolds combined with stem/progenitor cells is emerging as the response to the unsatisfactory outcome of approaches based solely on the injection of cells. Parenchymal and supporting cells are surrounded, in vivo, by a specialized and tissue-specific microenvironment, consisting mainly of extracellular matrix (ECM) and soluble factors incorporated in the ECM. Since the naturally occurring ECM is the ideal platform for ensuring cell engraftment, survival, proliferation, and differentiation, the acellular native ECM appears by far the most promising and appealing substrate among all biomaterials tested so far. To obtain intact scaffold of human native cardiac ECM while preserving its composition, we compared the decellularized ECM (d-ECM) produced through five different protocols of decellularization (named Pr1, Pr2, Pr3, Pr4, and Pr5) in terms of efficiency of decellularization, composition, and three-dimensional architecture of d-ECM scaffolds and of their suitability for cell repopulation. The decellularization procedures proved substantially different. Specifically, only three, of the five protocols tested, proved effective in producing thoroughly acellular d-ECM. In addition, the d-ECM delivered differed in architecture and composition and, more importantly, in its ability to support engraftment, survival, and differentiation of cardiac primitive cells in vitro.

Fibrillin-2 and Tenascin-C bridge the age gap in lung epithelial regeneration.

Organ engineering based on native matrix scaffolds involves combining regenerative cell populations with corresponding biological matrices to form functional grafts on-demand. The extracellular matrix (ECM) that is retained following lung decellularization provides essential structure and biophysical cues for whole organ regeneration after recellularization. The unique ECM composition in the early post-natal lung, during active alveologenesis, may possess distinct signals that aid in driving cell adhesion, survival, and proliferation. We evaluated the behavior of basal epithelial stem cells (BESCs) isolated from adult human lung tissue, when cultured on acellular ECM derived from neonatal (aged<1 week) or adult lung donors (n=3 donors per group). A significant difference in cell proliferation and survival was found. We next performed in-depth proteomic analysis of the lung scaffolds to quantify proteins significantly enriched in the neonatal ECM, and identified the glycoproteins Fibrillin-2 (FBN-2) and Tenascin-C (TN-C) as potential mediators of the observed effect. BESCs cultured on Collagen Type IV coated plates, supplemented with FBN-2 and TN-C demonstrated significantly increased proliferation and decreased cellular senescence. No significant increase in epithelial-to-mesenchymal transition was observed. Invitro migration was also increased by FBN-2 and TN-C treatment. Decellularized lung scaffolds treated with FBN-2 and TN-C prior to re-epithelialization supported greater epithelial proliferation and tissue remodeling. BESC distribution, matrix alignment, and overall tissue morphology was improved on treated lung scaffolds, after 3 and 7 days of exvivo lung culture. These results demonstrate that scaffold re-epithelialization is enhanced on neonatal lung ECM, and that supplementation of FBN-2 and TN-C to the native scaffold may be a valuable tool in lung tissue regeneration.

Heparin Augmentation Enhances Bioactive Properties of Acellular Extracellular Matrix Scaffold.

Extracellular matrix (ECM) maintains a reservoir of bioactive growth factors and matricellular proteins that provide bioinductive effects on local cells that influence phenotype and behaviors. Bioactive acellular ECM scaffolds can be used therapeutically to stimulate adaptive tissue repair. Fibroblast growth factor-2 (FGF-2) attenuates transforming growth factor-β1 (TGF-β1)-mediated cardiac fibrosis. Heparin glycosaminoglycan can influence FGF-2 bioactivity and could be leveraged to enhance tissue engineering strategies. We explored the effects of heparin on FGF-2 enhancement of bioactive ECM scaffold biomaterials for its antifibrotic effect on attenuating human cardiac myofibroblast activation. Increasing heparin concentration at a fixed concentration of FGF-2 markedly increased the amount of FGF-2 retained and eluted by ECM scaffolds. To explore synergistic bioinductive effects of heparin and FGF-2, collagen gel contraction assay using human cardiac myofibroblasts was performed in vitro. Myofibroblast activation was induced by profibrotic cytokine, TGF-β1. FGF-2 and heparin in combination reduced human cardiac myofibroblast-mediated collagen gel contraction to a greater extent than FGF-2 alone. These observations were confirmed for both human atrial and human ventricular cardiac fibroblasts. Cell death was not different between groups. In summary, heparin is an effective adjuvant to enhance FGF-2 loading and elution of acellular ECM scaffold biomaterials. Heparin increases the bioactive effects of FGF-2 in attenuating human cardiac myofibroblast activation in response to profibrotic TGF-β1. These data may inform tissue engineering strategies for myocardial repair to prevent fibrosis.

Establishment of rabbit radius fracture model and the role of stromal vascular fraction-acellular bone extracellular matrix-chitosan scaffold in promoting the healing of rabbits

Objective To prepare stable structure and good bone induction and biological compatibility of stromal vascular fraction (SVF)-acellular bone extracellular matrix(ABECM)-chitosan composite scaffold study SVF-ABECM-chitosan scaffolds to promote the healing of rabbit radius fracture. Methods Using Triton X-100 and sodium dodecyl sulfate (SDS) acellular method of porcine femur were decellularized, using a solution blending, freeze drying method preparing ABECM-chitosan composite scaffolds. The qualitative analysis of SVF-ABECM-chitosan scaffolds, observe SVF-ABECM-chitosan composite porous scaffold morphology, porosity, mechanical properties and cell scaffold composite culture compatibility.12 adult healthy New Zealand white rabbits were selected, and the fracture model was caused by the fracture gap of about 0.3 cm, which was exposed to the radial shaft of the radial side of the forearm of the rabbit. The SVF-ABECM-chitosan composite scaffold was prepared in the right radius fracture space of each animal, and the left side was the blank control group. The fracture healing was compared between the two sides of the radius fracture model of rabbits by X-ray, biomechanical test and tissue morphology. Results ABECM materials were stained with he and hoechest 33258 fluorescence staining showed no residual cells, immunohistochemical staining of alizarin red staining and type I collagen and bone morphogenetic occurred protein-2 antibody staining positive. Scanning election microscopy (SEM) showed that the scaffolds have a porous structure, the aperture 50-200 μm, porosity of (53.50±4.23)%, dry mechanical test support longitudinal compression modulus is (33.23±14.45) mPa, support wet state of compression modulus of (2.27±1.13) mPa. Cell scaffold composite culture has good compatibility. After 4 weeks and 12 weeks in the experimental group by X-ray films reflect the bone healing was stronger than that of the control group. After 12 weeks, the biomechanical test group in the maximum load, anti bending strength of HA load/displacement parameters and control group comparison differences were statistically significant, and elastic modulus difference were statistically significant (t=7.418, 5.131 and 2.838, P=0.004, 0.009 and 0.027), and elastic modulus difference between the two groups no statistical significance (t=1.455, P=0.064), at 12 weeks after operation, the histomorphometric results showed. In experimental group, the bone and shaping was significantly better than the control group. Conclusion Preparation of ABECM-CS composite porous scaffolds to cells completely, retained the removal of cells from the bone matrix main component, have the appropriate aperture and porosity, cell compatibility is good. SVF-ABECM-chitosan composite scaffold can effectively promote the healing of rabbit radius fracture. Key words: Stromal vascular fraction; Acellular bone matrix; Chitosan; Radius fracture; Rabbit

A biomimetic mesh for treating female stress urinary incontinence

For patients with medium to severe incontinence, sub-urethral support surgery has a high cure rate, but using synthetic meshes leads to some complications such as mesh erosion/exposure and thigh pain. Autologous or acellular extracellular matrix grafts present few complications but have a high recurrence rate. Regensling™ is a new sling product made of a synthetic material with a biomimetic structure, aiming to provide long-term mechanical support with a lower complication rate. To assess the safety and effectiveness of Regensling™, both in vitro and in vivo experiments were performed. The mesh was implanted in the subcutaneous, intramuscular and sub-urethral regions of rabbits. At 4, 12, and 26 weeks post-implantation, the animals were executed and the implants were studied for their mechanical and biocompatible properties. Compared to the control material, the Regensling™ was covered by a thin layer of fibrous tissue with good compliance, and had a milder inflammatory response. During the period of the experiment, Regensling™ showed stable strength with an increasing trend over time.

Uterine Fibroids Review: Understanding their Origins to Better Understand their Future Treatments

Despite the high prevalence and the enormous impact the uterine fibroids has on the healthcare system and the economy, there is no effective medical treatment available to eliminate fibroids. This is due in part to the fact that very little is known about their pathophysiology; in order to look for and potentially find treatments capable of eliminating fibroids, we must gain a deep understanding of the mechanisms behind their initiation, stimulation, and growth. In this article, we comprehensively review current knowledge of the pathogenesis of uterine fibroids, with the aim of better understanding their origin, as well as discussing the action of already existing medical treatments in order to highlight ways that potential future therapies may be able to target the disease. A literature search was performed in PubMed to find articles related to the etiopathogenesis of fibroids and their treatments. Myomas comprise areas of disordered smooth muscle fascicles characterized by an excess of acellular extracellular matrix (ECM) with a dysregulated phenotype. Although the initial event is believed to be smooth muscle cell proliferation, it is thought that a complex signaling system is also necessary. Non-hormonal factors may be responsible for initiating the development of uterine fibroids, although hormonal stimulation is an essential factor for their growth Recent studies have confirmed that the different cell types contained in fibroids are all clonally derived from a parental cell with implied multipotent stem cell properties. Ethnicity also strongly influences the development and clinical severity of fibroids. Many Growth factors and their respective receptors have been implicated in fibroid growth. The available evidence continues to reinforce the importance of progesterone in the development of fibroids. The Ulipristal Acetate mediated volume reduction is due to a series of multifactorial and successive events that lead to a low proliferation rate.

NEW PROGRESS OF ACELLULAR FISH SKIN AS NOVEL TISSUE ENGINEERED SCAFFOLD

To review the recent research progress of acellular fish skin as a tissue engineered scaffold, and to analyze the feasibility and risk management in clinical application. The research and development, application status of acellular fish skin as a tissue engineered scaffold were comprehensively analyzed, and then several key points were put forward. Acellular fish skin has a huge potential in clinical practice as novel acellular extracellular matrix, but there have been no related research reports up to now in China. As an emerging point of translational medicine, investigation of acellular fish skin is mainly focused on artificial skin, surgical patch, and wound dressings. Development of acellular fish skin-based new products is concerned to be clinical feasible and necessary, but a lot of applied basic researches should be carried out.

A Porcine Urinary Bladder Matrix Does Not Recapitulate the Spatiotemporal Macrophage Response of Muscle Regeneration after Volumetric Muscle Loss Injury

Volumetric muscle loss (VML) results in irrecoverable loss of muscle tissue making its repair challenging. VML repair with acellular extracellular matrix (ECM) scaffolds devoid of exogenous cells has shown improved muscle function, but limited de novo muscle fiber regeneration. On the other hand, studies using minced autologous and free autologous muscle grafts have reported appreciable muscle regeneration. This raises the fundamental question whether an acellular ECM scaffold can orchestrate the spatiotemporal cellular events necessary for appreciable muscle fiber regeneration. This study compares the macrophage and angiogenic responses including the remodeling outcomes of a commercially available porcine urinary bladder matrix, MatriStem™, and autologous muscle grafts. The early heightened and protracted M1 response of the scaffold indicates that the scaffold does not recapitulate the spatiotemporal macrophage response of the autograft tissue. Additionally, the scaffold only supports limited de novo muscle fiber formation and regressing vessel density. Furthermore, scaffold remodeling is accompanied by increased presence of transforming growth factor and α-smooth muscle actin, which is consistent with remodeling of the scaffold into a fibrotic scar-like tissue. The limited muscle formation and scaffold-mediated fibrosis noted in this study corroborates the findings of recent studies that investigated acellular ECM scaffolds (devoid of myogenic cells) for VML repair. Taken together, acellular ECM scaffolds when used for VML repair will likely remodel into a fibrotic scar-like tissue and support limited de novo muscle fiber regeneration primarily in the proximity of the injured musculature. This is a work of the US Government and is not subject to copyright protection in the USA. Foreign copyrights may apply. Published by S. Karger AG, Basel

Targeted proteomics effectively quantifies differences between native lung and detergent-decellularized lung extracellular matrices.

The extracellular matrix (ECM) in large part defines the biochemical and mechanical properties of tissues and organs; these inherent cues make acellular ECM scaffolds potent substrates for tissue regeneration. As such, they are increasingly prevalent in the clinic and the laboratory. However, the exact composition of these scaffolds has been difficult to ascertain. This paper uses targeted proteomics to definitively quantify 71 proteins present in acellular lung ECM scaffolds. We use this technique to compare two decellularization methods and demonstrate superior retention of ECM proteins important for cell adhesion, migration, proliferation, and differentiation in scaffolds treated with low-concentration detergent solutions. In the long term, the ability to acquire quantitative biochemical data about biological substrates will facilitate the rational design of engineered tissues and organs based on precise cell-matrix interactions.

A new method for the preparation of biomedical hydrogels comprised of extracellular matrix and oligourethanes

This paper reports a new method to modify hydrogels derived from the acellular extracellular matrix (ECM) and consequently to improve their properties. The method is comprised of the combination of liquid precursors derived from hydrolyzed acellular small intestinal submucosa (hECM) and water-soluble oligourethanes that bear protected isocyanate groups, synthesized from poly(ethylene glycol) (PEG) and hexamethylene diisocyanate (HDI). The results demonstrate that the reactivity of oligourethanes, along with their water solubility, properly induce simultaneously the polymerization of type I collagen and its crosslinking. The polymerization rate and the gel network parameters such as fiber diameter, porosity, crosslinking degree, mechanics, swelling, in vitro degradation and cell proliferation, keep a direct relationship with the oligourethane concentration. Consequently, the hybrid hydrogels formulated with 15 wt.% of oligourethane exhibit enhanced storage modulus and degradation resistance, while maintaining the cell viability and impeding the fibroblast-induced contraction in comparison with the hECM hydrogels without oligourethanes. Therefore, this method is adequate to prepare novel hydrogels where the adjustment of the crosslinking degree controls the materials structure and their properties. This new method offers advantages for regulating the features of ECM-derived templates, thereby extending their possibilities for tissue engineering (TE) applications.

The Human Pancreas as a Source of Protolerogenic Extracellular Matrix Scaffold for a New-generation Bioartificial Endocrine Pancreas.

Our study aims at producing acellular extracellular matrix scaffolds from the human pancreas (hpaECMs) as a first critical step toward the production of a new-generation, fully human-derived bioartificial endocrine pancreas. In this bioartificial endocrine pancreas, the hardware will be represented by hpaECMs, whereas the software will consist in the cellular compartment generated from patient's own cells. Extracellular matrix (ECM)-based scaffolds obtained through the decellularization of native organs have become the favored platform in the field of complex organ bioengineering. However, the paradigm is now switching from the porcine to the human model. To achieve our goal, human pancreata were decellularized with Triton-based solution and thoroughly characterized. Primary endpoints were complete cell and DNA clearance, preservation of ECM components, growth factors and stiffness, ability to induce angiogenesis, conservation of the framework of the innate vasculature, and immunogenicity. Secondary endpoint was hpaECMs' ability to sustain growth and function of human islet and human primary pancreatic endothelial cells. Results show that hpaECMs can be successfully and consistently produced from human pancreata and maintain their innate molecular and spatial framework and stiffness, and vital growth factors. Importantly, hpaECMs inhibit human naïve CD4 T-cell expansion in response to polyclonal stimuli by inducing their apoptosis and promoting their conversion into regulatory T cells. hpaECMs are cytocompatible and supportive of representative pancreatic cell types. We, therefore, conclude that hpaECMs has the potential to become an ideal platform for investigations aiming at the manufacturing of a regenerative medicine-inspired bioartificial endocrine pancreas.