Cells dervived from fat vs. bone marrow
Three techniques are available for treating tendon and ligament injuries with MSCs, according to Fortier. One involves using
mixed cells from adipose tissue, and the others make use of cultured cells from bone marrow or a centrifugation technique
to concentrate bone-marrow stem cells.
"You tend to get more nucleated cells from adipose tissue, so that might be one advantage, but what those cells are we don't
really know," Fortier says.
"Literature suggests that if you compare cells from fat and from bone marrow side by side, only looking at differentiation
of the cartilage and bone (for tendon, we don't really know), fat loses every time," Fortier says.
While acknowledging that "there is controversy in the literature," Bob Harman, DVM, MPVM and CEO of Vet-Stem Inc., of Poway,
Calif., says "an equal number of papers show that stem cells from adipose and bone marrow are equal in characteristics, including
differentiation ability into bone, cartilage, fat and other cell types." Vet-Stem provides a concentrated form of autologous,
adipose-derived adult stem and regenerative cells to practitioners, to treat traumatic and degenerative diseases.
"The reason we don't have the same information for tendon is that there are very few ways to mimic tendon development in the
laboratory, in contrast to the established ways we have to investigate development of new cartilage and bone," Fortier says.
"The superior cell type will come out within the next four to five years, when people have enough cases and clinically evaluate
Adipose-derived stem-cell therapy of the suspensory ligament injury in the horse showed a 76.6 percent return to prior level
of performance, according to a study by Harman and colleagues.
"I have not used many marrow-derived stem cells, but do use adipose-derived cells, mostly in conjunction with platelet-rich
plasma," says Lane Easter, DVM, Dipl. ACVS, with Performance Equine Associates in Whitesboro, Texas.
Platelet-rich plasma is thought to serve as a matrix for the stem cells to grow, and to add some growth factors. The jury
is still out on what growth factors actually do for stem cells and which growth factors are associated with different types
of platelet-rich plasma.
"The growth factors we get may not be the exact ones we need to turn that particular stem cell into whatever tissue we're
trying to grow," says Easter.
"The most promising type of cells in my view are those from bone marrow, the sternally derived stem cells," says John Peroni,
DVM, MS, Dipl. ACVS, at the University of Georgia College of Veterinary Medicine.
"I don't have any proof that they are better than the adipose-derived cells, so more work needs to be done to compare scientifically
the pros and cons of these two cell types. Evidence would suggest that the origin of the cells plays a role in their pluripotent
properties and it is possible that we will understand that the different cell types have different benefits and applications."
"We use the adipose-derived stem cells," says Garcia-Lopez. "In part, because of the ease of collection of the fat and the
ease of turnaround, and there are more potential stem cells in fat than in bone marrow, so we don't have to do the culturing,
as the group at Cornell does."