Doctor Niigata University Graduate School of Medical and Dental Sciences Niigata city, Japan
Abstract: The generation of pluripotent stem cells (PSCs)-derived lung tissues is one of the ultimate goals in the field of regenerative medicine. Fibroblast growth factor 10 (Fgf10) is a gene involved in the development of limbs and lungs in mice. Fgf10-/- mice present phenotypes indicating limb and lung deficiencies. We have earlier generated functional lung organs from mouse embryonic stem cells (ESCs) via blastocyst complementation in Fgf10 compound heterozygous mutant (Fgf10 Ex1mut/Ex3mut) mice. Here, we report the generation of rat lung tissues in interspecies rat-mouse chimeras using Fgf10 Ex1mut/Ex3mut model mice. A total of 1136 mouse blastocysts were microinjected with rat ESCs and 1107 of these blastocysts were transferred into pseudopregnant mouse uteri, and 242 neonates (21.9%) were obtained. Genotyping revealed that a total of 53 of 242 neonates (%) was derived from Fgf10 Ex1mut/Ex3mut blastocysts. A total of 13 of 242 neonates (5.3%) was identified as rat-mouse chimeras by confirming GFP expression and 5 of 53 (9.4%) Fgf10 Ex1mut/Ex3mut mice were confirmed as rat-mouse chimeras. 3 of 5 Fgf10 Ex1mut/Ex3mut rat-mouse chimeras exhibited limb deficiencies. Lung morphogenesis was confirmed in all of the Fgf10 Ex1mut/Ex3mut rat-mouse chimeras including those with limb deficiencies. However, lobes of lung even in Fgf10 Ex1mut/Ex3mut rat-mouse chimeras without limb deficiencies were fewer compared with those in wild type mice. Histological analysis exposed that rat lung tissues were generated from rat ESCs in Fgf10 Ex1mut/Ex3mut mice via blastocyst complementation. However, generated lung tissues were mosaic of ESCs and recipient cells in the parenchymal regions as well as in the interstitial regions. In spite of the low efficiency of generating rat-mouse chimeras and incomplete lung morphogenesis in Fgf10 Ex1mut/Ex3mut rat-mouse chimeras, these findings provide useful insights to generate lung tissues in an interspecies setting.
Funding Source: This work was supported by JSPS KAKENHI Grant Number 20H03741 and 24K11760
