Effect of partial pancreatectomy on diabetic status in BALB/c mice.

Pancreatic regeneration after pancreatectomy has been well documented in animal models. However, the phenomenon of pancreatic regeneration in diabetes has not been exploited as yet. We report here the restoration of euglycaemic status in streptozotocin (STZ)-induced diabetic BALB/c mice, after 50% pancreatectomy. We observed that, after pancreatectomy, STZ-diabetic mice showed a rapid improvement in glycaemic status, starting from the 8th postoperative day, and remained normoglycaemic throughout a 90-day follow-up study. STZ-induced diabetic and control non-diabetic BALB/c mice underwent pancreatectomy and were monitored regularly for changes in body weight, plasma glucose and serum insulin concentrations and histological status of the pancreas. All the pancreatectomised animals showed euglycaemic status from about 20 days after operation, whereas a majority (around 70%) of the diabetic, sham-operated animals died of sustained hyperglycaemia by 20-30 days after operation. Examination of the regenerating pancreas indicated nesidioblastotic activity and supported the theory of a ductal origin of islet stem cells. Islets isolated from the regenerating pancreas showed a progressive increase in islet area (1227.9+/-173.2 micrometer(2) on day 5 compared with 2473.8+/-242.0 micrometer(2) by day 20). The increment in insulin concentrations and subsequent decrement in glycaemia of the diabetic pancreatectomised animals indicate islet neogenesis occurring after the operative insult, leading to a normoglycaemic status, probably recapitulating ontogeny. We have shown that induction of a regenerative stimulus (pancreatectomy) in conditions of STZ-induced diabetes may trigger pancreatic regenerative processes, thereby restoring a functional pancreas, in STZ-diabetic mice

Islet-Like Cell Aggregates Generated from Human Adipose Tissue Derived Stem Cells Ameliorate Experimental Diabetes in Mice

BACKGROUND: Type 1 Diabetes Mellitus is caused by auto immune destruction of insulin producing beta cells in the pancreas. Currently available treatments include transplantation of isolated islets from donor pancreas to the patient. However, this method is limited by inadequate means of immuno-suppression to prevent islet rejection and importantly, limited supply of islets for transplantation. Autologous adult stem cells are now considered for cell replacement therapy in diabetes as it has the potential to generate neo-islets which are genetically part of the treated individual. Adopting methods of islet encapsulation in immuno-isolatory devices would eliminate the need for immuno-suppressants. METHODOLOGY/PRINCIPAL FINDINGS: In the present study we explore the potential of human adipose tissue derived adult stem cells (h-ASCs) to differentiate into functional islet like cell aggregates (ICAs). Our stage specific differentiation protocol permit the conversion of mesodermic h-ASCs to definitive endoderm (Hnf3β, TCF2 and Sox17) and to PDX1, Ngn3, NeuroD, Pax4 positive pancreatic endoderm which further matures in vitro to secrete insulin. These ICAs are shown to produce human C-peptide in a glucose dependent manner exhibiting in-vitro functionality. Transplantation of mature ICAs, packed in immuno-isolatory biocompatible capsules to STZ induced diabetic mice restored near normoglycemia within 3-4 weeks. The detection of human C-peptide, 1155±165 pM in blood serum of experimental mice demonstrate the efficacy of our differentiation approach. CONCLUSIONS: h-ASC is an ideal population of personal stem cells for cell replacement therapy, given that they are abundant, easily available and autologous in origin. Our findings present evidence that h-ASCs could be induced to differentiate into physiologically competent functional islet like cell aggregates, which may provide as a source of alternative islets for cell replacement therapy in type 1 diabetes

Islet neogenesis potential of human adult stem cells and its applications in cell replacement therapy for diabetes

In recent years regenerative biology has reached to greater heights due to its therapeutic potential in treating degenerative diseases; as they are not curable by modern medicine. With the advent of research in stem cells and developmental biology the regenerative potential of adult resident stem cells is becoming clearer. The long term objective of regenerative medicine or cell therapy is to treat patients with their own stem cells. These stem cells could be derived from the diseased organs such as skin, liver, pancreas etc. or from reservoirs of multipotent stem cells such as bone marrow or cord blood.Manipulating the ability of tissue resident stem cells as well as from multipotent reservoirs such as bone marrow, umbilical cord and cord blood to give rise to endocrine cells may open new avenues in the treatment of diabetes. A better understanding of stem cell biology would almost certainly allow for the establishment of efficient and reliable cell transplantation experimental programs in the clinic. We show here that multipotent mesenchymal stem cells can be isolated from various sources such as the bone marrow, placenta, umbilical cord. Upon stimulation with specific growth factors they differentiate into islet like clusters (ILCs). When ILCs obtained from the above mentioned sources were transplanted in experimental diabetic mice, restoration of normoglycemia was observed within three weeks of transplantation with concomitant increase in the body weight. These euglycemic mice exhibited normal glucose tolerance test indicating normal utilization of glucose. Allthough the MSCs isolated from all the sources had the same characteristics; they showed significant differences in their islet differentiation potential. ILCs isolated for the human bone marrow did not show any pancreatic hormones in vitro, but upon transplantation they matured into insulin and somatostatin producing hormones. Placental MSCs as well as ILCs showed insulin trascripts indicating their readiness towards islet lineage.These studies point towards futuristic therapeutic approach of auto-transplantation of bone marrow for diabetes. Our studies demonstrate that human bone marrow, umbilical cord and placenta have the potential to differentiate into islets. These alternative sources of stem cells for islet neogenesis will form the basis for generating large number of islets required for transplantation for diabetes reversal

Human Fallopian tube as a novel source of multipotent stem cells with potential for islet neogenesis

Presence of stem cells in the female genital tract has been reported; however stem cell status of Fallopian tube remains unexplored. In the present study, we show for the first time an existence of stem cells in a Fallopian tube.? A pure population of mesenchymal like cells was obtained from the Fallopian tube samples from patients undergoing hysterectomy. The immunocytochemistry of these cells revealed the presence of classical mesenchymal stem cell markers like smooth muscle actin, vimetin, nestin, desmin, CD44, CD90 and CD117.? These Fallopian Tube derived Mesenchymal stem cells could be induced to differentiate into adipocytes, chondrocytes, osteocytes, neuronal and pancreatic lineage under the influence of lineage specific differentiation cocktails. Such documentation of multipotent stem cells in a Fallopian tube may be of significance for instant repair of the tract as and when necessary so as to assist uninterrupted transport of eggs for possible fertilization thus facilitating reproduction

pH-sensitive freeze-dried chitosan-polyvinyl pyrrolidone hydrogels as controlled release system for antibiotic delivery

The aim of this study was to develop a pH-sensitive chitosan/polyvinyl pyrrolidone (PVP) based controlled drug release system for antibiotic delivery. The hydrogels were synthesised by crosslinking chitosan and PVP blend with glutaraldehyde to form a semi-interpenetrating polymer network (semi-IPN). The semi-IPN formation was confirmed by Fourier transform infrared spectroscopic (FTIR) analysis. Semi-IPNs, viz, air-dried and freeze-dried, were compared for their surface morphology, wettability, swelling properties and pH-dependent swelling. Air- and freeze-dried membranes were also incorporated with amoxicillin and antibiotic release was studied. Porous freeze-dried hydrogels (pore diameter, 39.20+/-2.66 mu m) exhibited superior pH-dependent swelling properties over non-porous air-dried hydrogels. A high octane contact angle (144.20+/-0.580) of hydrogel was indicative of its hydrophilic nature. Increased swelling of hydrogels, under acidic conditions, was due to the protonation of a primary amino group on chitosan, as confirmed by FTIR analysis. Freeze-dried membranes released around 73% of the amoxicillin (33% by air-dried) in 3 h at pH 1.0 and, thus, had superior drug-release properties to air-dried hydrogels. Freeze-dried membranes could serve as potent candidates for antibiotic delivery in an acidic environment. (C) 2000

Development and Characterization of Dual Growth Factor Loaded In Situ Gelling Biopolymeric System for Tissue Engineering Applications

In the past few decades, use of biodegradable scaffolds for tissue regeneration has emerged as a promising therapeutic approach with considerable success at clinical levels. The following study describes development of one such system an in situ gelling minimally invasive system using bacterial polysaccharides-Gellan and Xanthan as scaffolds for various tissue engineering applications. Gelation time studies for Gellan: Xanthan hydrogels was carried out to determine the most suitable ratio of the two gel components such that the gel mixture should remain a low viscosity fluid at room temperature but should form a highly viscous gel upon injection at the injury site (i.e., at body temperature) within a few minutes. The porous microstructure of the gels was observed by scanning electron micrographs (SEM) and transmission electron microscopy (TEM). A dual growth factor release system with platelet derived growth factors (PDGF-BB) and basic fibroblast growth factor (bFGF) was developed where growth factors were encapsulated within chitosan nanoparticles embedded in the gels as well as directly within the gel. Adipose tissue derived stem cell (ADSC) differentiation and production of glycosaminoglycans (GAG) was observed within 7 days as was tested by safranin-O staining. MU assay showed >90% viability for both L929 fibroblasts and ADSCs

Mineralization of nanohydroxyapatite on electrospun poly(L-lactic acid)/gelatin by an alternate soaking process: A biomimetic scaffold for bone regeneration

Biomimetic nanocomposite scaffolds were fabricated by electrospinning poly(l-lactic acid) and a blend of poly(L-lactic acid)/gelatin to eliminate the use of collagen. The scaffolds were mineralized via alternate soaking in calcium and phosphate solutions, whereby 66.8% nanohydroxyapatite formation was successfully induced which is similar to that of native human bone (60%). The poly(L-lactic acid)/gelatin scaffolds had uniform nanohydroxyapatite formation throughout the scaffold. The mineralization enhanced the tensile modulus and tensile strength without increasing the brittleness. The in vitro biocompatibility of scaffolds was evaluated with murine adipose tissue-derived stem cells. The scaffolds with nanohydroxyapatite aided cell attachment and promoted cell-cell interaction. The mineralization and osteocalcin expression of the murine adipose tissue-derived stem cells were maximum in the poly(L-lactic acid)/gelatin/nanohydroxyapatite scaffold. Therefore, the gelatin and nanohydroxyapatite in poly(L-lactic acid)/gelatin/nanohydroxyapatite scaffolds provided cues for the differentiation of murine adipose tissue-derived stem cells. The biochemical nature of poly(L-lactic acid)/gelatin/nanohydroxyapatite scaffold accelerated osteogenic differentiation and could be a potential candidate for bone regeneration

Generation of islet-like cell aggregates from human non-pancreatic cancer cell lines

To explore a novel source for the derivation of islets, we examined the differentiation potential of human non-pancreatic cancer cell lines, HeLa (cervical carcinoma cell line) and MCF-7 (breast cancer cell line). These cells were subjected to a serum-free, three-step sequential differentiation protocol which gave two distinct cell populations: single cells and cellular aggregates. Subsequent analysis confirmed their identity as pancreatic acinar cells and islet-like cell aggregates (ICAs), as evidenced by amylase secretion and diphenylthiocarbazone staining respectively. Reverse transcriptase-PCR and immunocytochemistry assessment of the ICAs revealed the expression of pancreatic specific markers Ngn-3, Glut-2, Pax-6 and Isl-1. These ICAs secreted insulin in response to glucose challenge, confirming their functionality. We propose that ICAs generated from HeLa and MCF-7 cell lines could form a promising in vitro platform of human islet equivalents (hIEQs) for diabetes research