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1.
Br J Med Med Res ; 2015; 8(7): 576-587
Article in English | IMSEAR | ID: sea-180690

ABSTRACT

Aims: Allogeneic bone marrow (BM) has been shown to support human islet survival and function in long-term culture by initiating human islet vascularization and β-cell regeneration. Various BM subpopulations may play different roles in human islet functions and survival. In this paper we investigated the effects of BM and its subpopulations, endothelial progenitor cells (E) and mesenchymal (M) cells on human islet’s β-cell function and regeneration. Study Design: Isolation and identification of subpopulations from human bone marrow and culture with allogeneic human islet to investigate effects of different cell population on human islet function and regeneration. Place and Duration of Study: Department of Medicine, Center for Stem Cell & Diabetes Research, RWMC, Providence, RI, USA, between 2010 - 2014. Methodology: Human islets were distributed from Integrated Islet Distribution Program (IIDP) and human bone marrow (BM) was harvested by Bone marrow transplantation center at Roger Williams Hospital. BM subpopulation was identified cell surface markers through Fluorescenceactivated cell sorting, applied in flow cytometry (FACS), islet function was evaluated by human ELISA kit and β cell regeneration was evaluated by three methods of Cre-Loxp cell tracing, β cell sorting and RT-PCR for gene expression. Results: Four different BM and seven different islet donates contributed human tissues. We observed islet β-cell having self regeneration capability in short term culture (3~5 days) using a Cre-Loxp cell tracing. BM and its subtype E, M have similar benefits on β cell function during coculture with human islet comparison to islet only. However, only whole BM enables to sustain the capability of islet β-cell self regeneration resulting in increasing β cell population while single E and M individual do not significantly affect on that. Mechanism approach to explore β-cell self regeneration by evaluating transcription factor expressions, we found that BM significantly increases the activations of β-cell regeneration relative transcription factors, the LIM homeodomain protein (Isl1), homologue to zebrafish somite MAF1 (MAFa), the NK-homeodomain factor 6.1 (NKX6.1), the paired box family factors 6 (PAX6), insulin promoter factor 1 (IPF1) and kinesin family member 4A (KIF4a). Conclusion: These results suggest that BM and its derived M and E cells enable to support human islet β-cell function. However, only BM can sustain the capability of β-cell self regeneration through initiating β-cell transcriptional factors but not individual E and M cells suggesting pure E and M cells less supportive for islet long-term survival in vitro.

2.
Chinese Journal of Practical Internal Medicine ; (12)2006.
Article in Chinese | WPRIM | ID: wpr-562543

ABSTRACT

Objective This study aimed to investigate the effects of angiotensin Ⅱ and Losartan pretreatment on regulating insulin secretion in human islet ? cells.Methods We measured changes in intracellular calcium by confocal laser scanning microscopy using Flou3-AM-loaded human islet cells.RT-PCR was used to measure changes in intracellular CaM.Dynamic insulin secretory responses were determined by chemiluminescence following perfusion of human islets.Results Exposure of the isolated islets to angiotensin Ⅱ induced glucose-stimulated insulin release coupled with intracellular calcium ascending in first phase and descending in second phase.Intracellular CaM concentration could not be affected by angiotensin Ⅱ.Conclusion The change of free Ca2+is induced by the combination of AngⅡ with ATI receptors of islet B cells,which results in the damage to islet B cells.Losartan pretreatment protects the islet B-cell function by inhibiting calcium overload.

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