A high-quality RNA-yielding protocol for laser capture microdissection of transplanted stem cell-derived Islets of Langerhans

Laser capture microdissection (LCM) followed by RNA-sequencing is a powerful, widely applicable tool to analyze the transcriptome in regions of a tissue. Protocols for LCM of transplanted islets of Langerhans, particularly stem cell-derived islets (SC-islets) that have evaluated RNA quality, are lacking. This study demonstrates a robust protocol for LCM of SC-islets in multiple organ sites, generating high quality RNA. SC-islets were transplanted to five organ sites in immunodeficient NOG-mice. Graft-containing organs were then sectioned, fixed in 75% ethanol, stained with the alcohol-based stain cresyl violet, and dehydrated before performing LCM. RNA was then extracted, and quality control was performed. High RIN scores (RNA Integrity Number) were obtained from all organ sites, with the pancreas showing the most robust results, despite its known challenges due to high RNase content. Conversely, organs with small or dispersed grafts, such as the liver and omentum, exhibited lower RIN scores. This is likely due to the size of the dissected area correlating positively with RIN scores, potentially due to a more time-consuming LCM in these sites. Using this novel protocol, high-quality RNA from transplanted SC-islets can be obtained. Smaller and spread-out grafts pose a challenge in obtaining higher quality RNA, although possible.