Safety, stem cell viability, and osteochondral activity after repeat intra-articular allogeneic mesenchymal stem cell injections in MHC mismatched horses

Author

Layla M. Gray, University of Tennessee, KnoxvilleFollow

Date of Award

5-2024

Degree Type

Thesis

Degree Name

Master of Science

Major

Comparative and Experimental Medicine

Major Professor

Elizabeth M. Collar

Committee Members

Elizabeth M. Collar, Madhu S. Dhar, Darryl L. Millis

Abstract

The safe use of allogeneic bone marrow derived mesenchymal stem cells (BM-MSCs) in horses has been established, but efficacy and safety are still controversial. Investigations have been limited to repeat injections from one donor only.

Two geldings served as MHC mis-matched BM-MSC donors. Twelve mares (AAEP lameness grade ≤3/5) were divided into control (unilateral limb) and recipient (stem cell and internal control limbs) groups. Synovial fluid (SF) collected on days 0, 7, 21, 28, and 42 underwent cytologic analyses and SF-MSCs culture (cultured cells were DNA haplotyped). Biomarkers analyses of cartilage formation (CPII), cartilage degradation (C2C), bone formation (Osteocalcin), bone resorption (CTX-I), and inflammation (PGE₂) using commercial ELISA kits were performed on serum and synovial fluid collected on days 0, 7, 21, and 28. Physical and lameness evaluations were performed pre- and post- injections.

Total nucleated cell count (TNCC) was never above normal limits for any joint. Stem cell treated joints had higher TNCC than all control joints at days 21-42 (p≤0.0021). All joints were within normal parameters for neutrophil percentage with no difference between treatment groups. Limb edema and joint effusion were greater in stem cell limbs than control limbs 1-7 days following injections. Stem cell limbs had an increased lameness at a trot 24 hours following the second injection (p=0.04), which returned to baseline by 72 hours. . SF-MSCs were grown from all joints, and were verified to be from recipient horses in stem cell joints. Cells in culture took longer to reach first passage in all groups from day 0 to 21 and 42. Stem cell treated joints had a greater increase in CPII than C2C following injections, with higher SF CPII than internal control joints 7 days (p≤0.019) but not 21 days following injections. Stem cell joints were higher in OC than internal controls on day 21 (p=0.027) only, with no change in CTXI.

In conclusion, allogeneic BM-MSCs from two different MHC-mismatched donors appears to be safe for intra-articular injection, with some short-term inflammation after repeat intra-articular injection. The primary changes in osteochondral activity were an increase in cartilage synthesis with minimal change in bone activity.

Recommended Citation

Gray, Layla M., "Safety, stem cell viability, and osteochondral activity after repeat intra-articular allogeneic mesenchymal stem cell injections in MHC mismatched horses. " Master's Thesis, University of Tennessee, 2024.
https://trace.tennessee.edu/utk_gradthes/11380