Reduced Immunogenicity of First-Trimester Human Fetal Pancreas

Abstract

OBJECTIVE-The use of human fetal pancreatic tissue may provide a potential source of transplantable ␤-cells as a therapy for type 1 diabetes. Human fetal pancreas has a remarkable capacity to grow and differentiate in vivo and has been shown to reverse diabetes in rodents. However, it is known that human fetal pancreas obtained from the second trimester of gestation is immunogenic and is rejected after transplantation. Tissue obtained from earlier stages might prove to be immune privileged, as has been shown for other tissues.RESEARCH DESIGN AND METHODS-In this study, we determined the immunogenicity of human fetal pancreatic tissue obtained from the first trimester of gestation in a humanized mouse model. A microarray study of immunoregulatory gene expression in first-and second-trimester human fetal pancreas was also undertaken.RESULTS-The analysis of transplanted human fetal pancreata revealed a significantly decreased immunogenicity of the firsttrimester tissue. The first-trimester grafts showed only limited cellular infiltration and contained numerous insulin-positive cells, whereas second-trimester tissue was completely infiltrated and rejected. Furthermore an analysis of immunoregulatory genes expressed in first-and second-trimester human fetal pancreas by microarray demonstrated the upregulation of several key immunoregulatory genes in the second-trimester tissue. This might account for the reduced immunogenicity of the younger tissue.CONCLUSIONS-Our results provide the first indication that the use of first-trimester human fetal pancreas for transplantation might increase the survival of the grafts and might decrease the requirement for immunosuppressive drugs. Diabetes 57:627-634, 2008

Transcription factor expression in the developing human fetal endocrine pancreas

“…2). Affymetrix GCOS 1.2 (Affymetrix) and GeneSpring version 7.1 (Agilent Technologies Canada, Mississauga, ON, Canada) software were used to examine expression levels [21]. Data were then normalised using Robust Multichip Analysis (RMA) to show expression relative to data for 8 to 10 weeks.…”

“…RNA quality was verified by agarose gel electrophoresis using ethidium bromide staining and by Agilent 2100 Bioanalyzer Scans (Agilent Technologies, Palo Alto, CA, USA) using a kit (RNA 6000 Nano kit RNA Quality; Caliper Life Sciences, Mountain View, CA, USA), as described previously [21]. Biotinylated complimentary RNA was generated and hybridised to Affymetrix HG-U133A GeneChips (Affymetrix, Santa Clara, CA, USA) [21].…”

“…Relative gene expression was calculated using the arithmetic formula 2 ÀΔΔC T , where C T is the difference between the threshold cycle of a given target cDNA and the internal standard gene 18S rRNA subunit cDNA. Relative PCR signals from middle and late stages were normalised to early stage data [21,23].…”

“…RT-PCR and real-time RT-PCR To validate gene expression levels obtained from microarray analyses, quantitative realtime RT-PCR assays were performed with a kit (iQ SYBR Green Supermix, VWR, Mississauga, ON, Canada) in Chromo4 Real-Time PCR (Bio-Rad Laboratories, Mississauga, ON, Canada), as described previously [21,22]. PCR primers are listed in ESM Table 3.…”

Fibrin supports human fetal islet-epithelial cell differentiation via p70s6k and promotes vascular formation during transplantation

“…7 Transplantation of human fetal pancreata has been suggested as a treatment alternative for diabetes due to its reduced immunogenic nature. 28 Indeed, transplantation of human fetal pancreatic cells into athymic diabetic mice leads to normo-glycemia 29 and the use of fibrin may assist in graft survival and function. 25,30 Therefore, the objective of this study is to analyze whether fibrin can promote human fetal pancreas differentiation and proliferation in vitro and in vivo as well as the potential mechanisms involved.…”