Needle Optimization Study for Equine BMSC Injections

Abstract

Stem cell treatments are used to treat tissue and cartilage ailments in veterinary regenerative medicine. Three-dimensional spheroid equine bone marrow mesenchymal stem cells (eBMSC) can be used in clinical practice due to their increased anti-inflammatory and regenerative properties as opposed to 2D monolayer stem cells. The standard for veterinarians is to inject stem cells through 22G, 20G and 18G needles with respective diameters of 413μm, 603μm, and 838μm. Spheroid cells are injected with these needles while having an average size of 300-400μm. Smaller needles have the potential to shear stem cells which may lead to early-onset apoptosis and decreased viability. Here we show that 20G and 22G needles show decreased viability for spheroid injection. While not statistically significant, therefore inconclusive at this time, we found that spheroid eBMSC average viability decreased from 85% in the control group to 61% in the 22G treatment group. Interestingly, the 2D monolayer stem cell culture showed an opposite trend of increased viability with smaller needle sizes. A replication of the experiment will be helpful to identify if larger needle sizes reduce the viability of monolayer and spheroid eBMSC, and which needle gauge is optimal for clinical use. We anticipate our needle optimization study to be the basis on which clinicians begin to incorporate needle sizes that ensure the highest stem cell viability and start exploring the use of spheroid cell culture in treating osteoarthritis, and other like ailments in veterinary medicine.