A Novel, Proprietary Intravenous Delivery Solution Sustains Feline Adipose-Derived Mesenchymal Stem Cell Viability and Function for 7 Days at Cold Temperature

Presented by: Chad B. Maki


Authors: Chad B. Maki1*, Naomi J. Walker2, Ubaldo De La Torre2, Dori Borjesson2, Sean Owens2

Affiliations: 1VetCell Therapeutics USA™, 2917 Daimler St, Santa Ana, CA 92705, 2 Veterinary Institute for Regenerative Cures and the Department of Pathology, Microbiology & Immunology, School of Veterinary Medicine, University of California Davis

Introduction: Mesenchymal Stem Cell (MSC) therapeutic research has been investigated for many years and is currently in the spotlight for numerous human and veterinary clinical trials. Historically, researchers have tried to develop “off the shelf” allogeneic therapies that can be administered directly from a thawed vial, but evidence in support of fresh cultured MSCs for safety and efficacy is growing. Providing fresh-cultured MSCs for therapy is logistically complex and cells are only viable for 48hrs. To alleviate this restriction, we are developing a proprietary solution (Sol-1) appropriate for intravenous administration that sustains viability and function for 7 days at 4°C.

Hypothesis / Objectives: We hypothesize that the VetCell Therapeutics USA™ (VCT-USA) proprietary delivery solution (Sol-1) will sustain the health of feline adipose-derived MSCs (FAD-MSCs) for an extended period of days at 4°C as measured by cell viability and the ability to inhibit lymphocyte proliferation in vitro in a mixed leukocyte reaction (MLR) assay.

Materials and Methods: FAD-MSCs were derived from young, healthy, screened cat donors in VCT-USA’s ISO-7 clean room and GMP compliant veterinary bio-manufacturing facility. They were cryopreserved at Passage 2 (P2) and met extensive standards for safety and characterization. At UC Davis, cells were cultured to P3 for 2-3 days. Cells were loaded into glass vials with a screw cap at 10 x 106 cells/ml and maintained at 4°C. At 24hr time points, aliquots were checked for identity, cell retention, viability and solution stability. Furthermore, cells were tested in an MLR assay at Day 0, Day 3 and Day 7.

Results: In most solutions tested (LRS, AS-3 Nutricel®, AS-5 Optisol® and DPBS), cell viability decreased to <70% after 48hrs at 4°C. Cells stored in Sol-1 had sustained cell viability and functionality up to 7 days. At Day 7, cells had an average viability of 84.2% with minimal cell loss. Cells successfully inhibited lymphocyte proliferation (>20% inhibition) and actively secreted immunomodulatory cytokines prostaglandin E2 (PGE2) and indoleamine 2,3-dioxygenase (IDO). Cells maintained expression of MSC surface protein CD105 and did not upregulate MHC II expression. Solutions passed sterility and maintained stable pH, K+, Na+, Ca2+, Cl-, Glu, Lac levels.

Conclusions: For the first time, we have achieved extended storage of MSCs at 4°C in a solution that is appropriate for intravenous administration. Producing fresh cultured MSCs for therapy has inherent logistical difficulties. Sol-1 may offer flexibility with MSC production, shipping, and patient scheduling. The next steps are to take the necessary regulatory actions to develop Sol-1 into a product that is approved for intravenous administration and to test in vivo efficacy of MSCs suspended in solution for 7 days, in a well-established disease model for MSC therapy such as feline chronic gingivostomatitis (FCGS).

Acknowledgements, Funding, and Conflicts of Interest: We would like to thank VCT-USA’s bio-manufacturing team for the derivation of consistent, high quality feline MSC cell lines for this study and for the continued guidance and support of Mr. Thomas Yuen. This study was funded by VetCell Therapeutics USA™. Chad B. Maki is an employee at VCT-USA.