Distribution of injected technetium^99m‐labeled mesenchymal stem cells in horses with naturally occurring tendinopathy

Abstract

This study aimed to investigate immediate cell survival and distribution following different administration routes of mesenchymal stem cells (MSCs) into naturally occurring tendon injuries. Ten million MSCs, labeled with technetium-99m hexamethylpropyleneamine oxime, were implanted into 13 horses with naturally occurring tendon or ligament injuries intra-lesionally, intravenously and by regional perfusion, and traced for up to 48 h using planar gamma scintigraphy. Labeling efficiencies varied between 1.8% and 18.5% (mean 9.3%). Cells were retained in the damaged area after intra-lesional administration but only 24% of cells were still present within the tendon after 24 h. After intravenous injection, cells largely distributed to the lung fields, with no detectable cells in the tendon lesions. Significant labeling of the tendon lesions was observed in 11/12 horses following regional perfusion but at a lower level to intra-lesional injection. The highest cell numbers were retained after intra-lesional injection, although with considerable cell loss, while regional perfusion may be a viable alternative for MSC delivery. Cells did not "home" to damaged tendon in large numbers after intravenous administration. Cells were detected in the lungs most frequently after intravascular administration, although with no adverse effects. Low cell retention has important implications for designing effective clinical therapies for human clinical use. #

The Current ‘State of Play’ of Regenerative Medicine in Horses: What the Horse Can Tell the Human

“…An alternative tracking method is to label MSCs with hexamethylpropyleneamine oxime (HMPAO) and Technetium99m (Tc99m), which allows in vivo tracking using a gamma camera. MSCs labeled with Tc99m have been used in both normal and experimentally created lesions [83,84] and in horses with naturally occurring tendinopathy [85]. In spite of the different experiments there was remarkable similarity in cell retention 24 hours after intralesional injection, where only 24% of implanted cells remained.…”

Adipose tissue as mesenchymal stem cells source in equine tendinitis treatment

“…This result meets that in previous studies, which have used MSCs from the bone marrow marked with technetium 99m to intralesional administration in the SDFT. The presence of marked cells in the implantation area was observed, as well as their presence in organs such as the lung (BECERRA et al, 2013).…”

Achilles Tendon Injuries in Elite Athletes: Lessons in Pathophysiology from Their Equine Counterparts

“…On a positive note, recent and ongoing developments in imaging are now making it possible to obtain greater value out of in vivo studies (e.g., cell-based therapies) in both horses and human patients. These include magnetic resonance imaging of magnetically labeled cells and gamma scintigraphic imaging of cells labeled with radionuclides (used to monitor stem cells injected into SDFT lesions) (Becerra et al 2013;Kjaer et al 2008). …”