181 Establishment of Induced Pluripotent Stem Cells from Fishing Cat and Clouded Leopard Using Integration-Free Method for Wildlife Conservation

Abstract

Fishing cat (Prionailurus viverrinus) and clouded leopard (Neofelis nebulosa) are wild felids, currently in vulnerable status according to the International Union for Conservation of Nature red list (2017). Several measures in assisted reproductive technology (e.g. AI, embryo transfer) have been used by the Zoological Park Organization of Thailand (ZPO) to increase their offspring in captivity. Recently, the generation of induced pluripotent stem cell (iPS cells) becomes popular and provides alternative way to preserve good genetics in the form of cell with diverse capacities. This great potential of iPS cells is unlimited self-renewal and pluripotency, similar to embryonic stem cells (ESC). Under the right cell culture conditions, pluripotent stem cells can differentiate into all cell types of the body. Here, we aimed to find the optimal condition to generate integration-free iPS cells from fishing cat and clouded leopard. At first, to obtain somatic cells for cellular reprogramming, adult dermal fibroblast cell lines from both species were established from belly skin tissues. Subsequently, several nucleofection programs of Amaxa^TM 4D-nucleofector^TM (Lonza, Basel, Switzerland) were examined to introduce integration-free DNA vectors carrying reprogramming factors into the felid fibroblasts. The transfected cells were cultured under numerous conditions: (1) matrix/defined surface including irradiated mouse embryonic fibroblast, gelatin, vitronectin, and Geltrex® (Thermo Fisher Scientific, Waltham, MA, USA); (2) ESC/iPS cell medium including Essential 8^TM (Thermo Fisher Scientific) DMEM containing KnockOut^TM Serum Replacement (KOSR; Thermo Fisher Scientific) and/or fetal bovine serum (FBS); and (3) supplement including basic fibroblast growth factor (bFGF), leukemia inhibitory factor (LIF), l-ascorbic acid, nicotinamide, ALK5 inhibitor (A83-01) and RevitaCell^TM (Thermo Fisher Scientific). We found that optimal nucleofection programs for human dermal fibroblast including FF-135 and EN-150 were able to transfer episomal vectors and excisable piggyBAC transposon carrying reprogramming factors into fishing cat and clouded leopard fibroblasts, respectively. The iPS-like colonies appeared around 26 to 30 days post-nucleofection. The culture of transfected cells on either Geltrex® or Vitronectin-coated surface supports the formation of iPS-like colonies with different derivation efficiency (0.01 and 0.005%, respectively). In addition, all colonies were formed under medium containing FBS, together with both bFGF and LIF supplements. Taken together, we have developed a platform to generate iPS cells from tissue collection to the establishment of iPS cell culture. This will further enable us to apply the technique to obtain iPS cells from other endangered and vulnerable felid species.