Objective—To compare the mesenchymal stem cell (MSC) yield and chondrogenic and osteogenic differentiation from 5- and 50-mL bone marrow aspirates from horses.
Animals—Six 2- to 5-year-old mixed-breed horses.
Procedures—2 sequential 5-mL aspirates were drawn from 1 ilium or sternebra. A single 50-mL aspirate was drawn from the contralateral ilium, and 2 sequential 50-mL aspirates were drawn from a second sternebra. The MSC yield was determined through the culture expansion process. Chondrogenesis and osteogenesis were evaluated by means of conventional laboratory methods.
Results—The second of the 2 sequential 50-mL sternal aspirates yielded few to no MSCs. Independent of location, the highest density of MSCs was in the first of the 2 sequential 5-mL fractions, although with subsequent culture expansion, the overall yield was not significantly different between the first 5-mL and first 50-mL fractions. Independent of location, chondrogenesis and osteogenesis were not significantly different among fractions. Independent of fraction, the overall cell yield and chondrogenesis from the ilium were significantly higher than that from the sternum.
Conclusions and Clinical Relevance—This study failed to detect an additional benefit of 50-mL aspirates over 5-mL aspirates for culture-expanding MSCs for equine clinical applications. Chondrogenesis was highest for MSCs from ilial aspirates, although it is not known whether chondrogenesis is indicative of activation of other proposed pathways by which MSCs heal tissues.
Objective—To evaluate healing of pinch-grafted
wounds on the distal aspect of the limbs of ponies
bandaged with equine amnion or a standard nonadherent
wound dressing material.
Procedure—A 2.5 × 2.5-cm full-thickness section of
skin was removed from the dorsal aspect of each
limb at the midpoint of the metacarpus or metatarsus.
Six days later, wounds were grafted with partial-thickness
pinch grafts. Half the wounds were bandaged
with amnion, and the other half were bandaged with
a nonadherent dressing. Bandages were changed
every 3 days until wound healing was complete. At
each bandage change, numbers of grafts lost were
recorded, and wounds were measured.
Results—Percentage of grafts lost from wounds bandaged
with amnion was not significantly different
from percentage lost from wounds bandaged with
the nonadherent dressing. Median healing time for
wounds bandaged with amnion (30 days) was significantly
less than median healing time for wounds bandaged
with the nonadherent dressing (39 days). All
wounds were healed by day 45.
Conclusions and Clinical Relevance—Results suggest
that amnion can be used for bandaging pinchgrafted
wounds on the distal aspect of the limbs of
ponies. (Am J Vet Res 2000;61:326–329)
Objective—To evaluate the effect of fibrin concentrations on mesenchymal stem cell (MSC) migration out of autologous and commercial fibrin hydrogels.
Sample—Blood and bone marrow from six 2- to 4-year-old horses.
Procedures—Autologous fibrinogen was precipitated from plasma and solubilized into a concentrated solution. Mesenchymal stem cells were resuspended in fibrinogen solutions containing 100%, 75%, 50%, and 25% of the fibrinogen precipitate solution. Fibrin hydrogels were created by mixing the fibrinogen solutions with MSCs and thrombin on tissue culture plates. After incubation for 24 hours in cell culture medium, the MSCs that had migrated onto the tissue culture surface and beyond the boundary of the hydrogels were counted. This procedure was repeated with a commercial fibrin sealant.
Results—Hydrogel-to-surface MSC migration was detected for all fibrin hydrogels. Migration from the 25% autologous hydrogels was 7.3-, 5.2-, and 4.6-fold higher than migration from 100%, 75%, and 50% autologous hydrogels, respectively. The number of migrating cells from 100%, 75%, and 50% autologous hydrogels did not differ significantly. With commercial fibrin sealant, the highest magnitude of migration was from the 25% hydrogels, and it was 26-fold higher than migration from 100% hydrogels. The 75% and 50% hydrogels resulted in migration that was 9.5- and 4.2-fold higher than migration from the 100% hydrogels, respectively.
Conclusions and Clinical Relevance—MSC migration from fibrin hydrogels increased with dilution of the fibrinogen component for both autologous and commercial sources. These data supported the feasibility of using diluted fibrin hydrogels for rapid delivery of MSCs to the surface of damaged tissues.