Objective—To characterize equine muscle tissue– and periosteal tissue–derived cells as mesenchymal stem cells (MSCs) and assess their proliferation capacity and osteogenic potential in comparison with bone marrow– and adipose tissue–derived MSCs.
Sample—Tissues from 10 equine cadavers.
Procedures—Cells were isolated from left semitendinosus muscle tissue, periosteal tissue from the distomedial aspect of the right tibia, bone marrow aspirates from the fourth and fifth sternebrae, and adipose tissue from the left subcutaneous region. Mesenchymal stem cells were characterized on the basis of morphology, adherence to plastic, trilineage differentiation, and detection of stem cell surface markers via immunofluorescence and flow cytometry. Mesenchymal stem cells were tested for osteogenic potential with osteocalcin gene expression via real-time PCR assay. Mesenchymal stem cell cultures were counted at 24, 48, 72, and 96 hours to determine tissue-specific MSC proliferative capacity.
Results—Equine muscle tissue– and periosteal tissue–derived cells were characterized as MSCs on the basis of spindle-shaped morphology, adherence to plastic, trilineage differentiation, presence of CD44 and CD90 cell surface markers, and nearly complete absence of CD45 and CD34 cell surface markers. Muscle tissue–, periosteal tissue–, and adipose tissue–derived MSCs proliferated significantly faster than did bone marrow–derived MSCs at 72 and 96 hours.
Conclusions and Clinical Relevance—Equine muscle and periosteum are sources of MSCs. Equine muscle- and periosteal-derived MSCs have osteogenic potential comparable to that of equine adipose- and bone marrow–derived MSCs, which could make them useful for tissue engineering applications in equine medicine.
Objective—To determine changes in the distal ends
of the third metacarpal and metatarsal bones (MCIII
and MTIII) of Thoroughbred racehorses that had sustained
a catastrophic condylar fracture during highspeed
Sample Population—Fractured and contralateral
MCIIIs and MTIIIs from 11 Thoroughbred racehorses
that sustained a displaced condylar fracture during
racing, both MCIIIs from 5 Thoroughbred racehorses
euthanatized because of a catastrophic injury other
than a condylar fracture, and both MCIIIs from 5 horses
of other breeds that had not been professionally
trained or raced.
Procedure—Macroscopic observations were made
of the distal ends of the bones before and after digestion
of the articular cartilage with NaOH.
Results—In all 11 racehorses with a displaced condylar
fracture, the fracture was associated with a
branching array of cracks in the condylar groove. In
this region, fracture margins were smooth, and there
was loss of subchondral bone. Comminution of the
dorsal cortex was also seen. Parasagittal linear wear
lines in the articular cartilage, erosions in the articular
cartilage of the condyles, loss of the underlying subchondral
bone, and cracking of condylar grooves were
all more severe in the Thoroughbred racehorses than
in the horses that had not been professionally trained
Conclusions and Clinical Relevance—Results suggest
that condylar fractures in horses are pathologic
fatigue or stress fractures that arise from a preexisting,
branching array of cracks in the condylar groove
of the distal end of MCIII or MTIII. (Am J Vet Res 2003;64:1110–1116)