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  • Author or Editor: Allison A. Worster x
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Abstract

Objective—To determine the morphologic and phenotypic effects of transforming growth factor β1 (TGF-β1) on cultured equine mesenchymal stem cells (MSC) and articular chondrocytes.

Sample Population—Bone marrow aspirates and articular cartilage samples from a 2-year-old and two 8- month-old horses.

Procedure—After initial isolation and culture, MSC and chondrocytes were cultured in Ham's F-12 medium supplemented with TGF-β1 at a concentration of 0, 1, 5, or 10 ng/ml. Medium was exchanged on day 2, and cells were harvested on day 4. Medium was assayed for proteoglycan (PG) content. Total RNA was isolated from cell cultures, and expression of aggrecan, decrin, collagen type-I, and collagen type-II mRNA was assessed by means of Northern blot analyses. Cell cultures were stained with H&E or toluidine blue and examined histologically. Additional cultures were examined after immunohistochemical staining for type-I and -II collagen.

Results—MSC cultures exposed to TGF-β1 had an increased cellular density with cell layering and nodule formation that was most pronounced in cultures treated with 5 ng of TGF-β1/ml. Expression of collagen type-II mRNA in MSC cultures exposed to 5 ng of TGF- β1/ml was 1.7 times expression in control cultures, and expression of collagen type-I mRNA was 2.8 times expression in control cultures. Treatment of MSC with TGF-β1 led to dose-related increases in area and intensity of type-II collagen immunoreaction.

Conclusion—Results suggest that TGF-β1 enhances chondrogenic differentiation of bone marrow-derived MSC in a dose-dependent manner. (Am J Vet Res 2000;61:1003–1010)

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine alteration in adrenocortical function in horses with recurrent airway obstruction (heaves) after aerosol and parenteral administration of beclomethasone dipropionate and dexamethasone, respectively.

Animals

6 horses with inducible and reversible heaves.

Procedure

Episodes of heaves were induced by exposure to moldy hay and straw for 7 days (natural challenge). Horses then underwent treatment (aerosolized beclomethasone, parenterally administered dexamethasone, and aerosolized propellant) for 7 days. Horses remained in the mold-contaminated environment for 7 days after discontinuation of drugs. Adrenocortical function was determined by serial evaluation of Cortisol concentration in serum obtained on days 0, 7, 9, 12, 14, 16, 19, and 21. Adrenocorticotropic hormone stimulation testing was performed in 4 horses/treatment group on days 0, 7, 14, and 21.

Results

Endogenous Cortisol production was suppressed in beclomethasone- and dexamethasone-treated horses within 2 days of treatment but recovered to values similar to those in propellant-treated horses approximately 2 and 4 days after discontinuation of drugs. Serum Cortisol concentration in propellant-treated horses gradually decreased during the study and was significantly lower than baseline on days 14, 16, 19, and 21. Mean increase in serum Cortisol concentration in response to ACTH stimulation testing after beclomethasone and dexamethasone administration did not differ significantly from the response observed in propellant-treated horses.

Conclusions

Aerosol and parenteral administration of beclomethasone and dexamethasone, respectively, suppressed adrenocortical function; however, endogenous cortisol production resumed approximately 2 and 4 days after discontinuation of drugs. Responsiveness to ACTH stimulation testing was not affected by the 7-day treatment period. (Am J Vet Res 1998;59:1044–1047)

Free access
in American Journal of Veterinary Research