Abstract
The objective of this report was to evaluate myofibroblast numbers in human elbow anterior joint capsules. Joint capsules were obtained from six patients with post-traumatic contractures and from six elbow joints of age-matched organ donors. Frozen sections were labeled with α-smooth muscle actin (α-SMA), a marker of myofibroblasts. Myofibroblasts were identified in both experimental and control tissues. Myofibroblast numbers and percentage of total cells were significantly elevated in the capsules of patients (919 ± 187; 36 ± 0.04%) when compared to organ donor control tissue (485 ± 335; 9 ± 0.04%). Future work will look at the expression of myofibroblast modulators in human elbow joint contractures.
The purpose of this study was to determine whether myofibroblasts are associated with human elbow joint contractures.
Myofibroblast numbers and percentage of myofibroblasts to total cells were significantly increased in anterior elbow joint capsules of patients with post-traumatic contractures.
Methods to alter myofibroblast expression may be strategies to prevent or treat post-traumatic elbow joint contractures.
Joint capsules were obtained from six patients (age 33±13 yrs, preoperative flexion-extension arc range of motion 58°±15°) and from six elbow joints of organ donors free of contractures (age 26±15 yrs). Frozen sections were double labeled using monoclonal antibodies to α-smooth muscle actin (α-SMA) with peroxidase conjugated secondary antibodies, and affinity purified antibodies to laminin with Elexa Fluor 488 conjugated secondary antibodies. The laminin antibodies label components of blood vessels, to differentiate between α-SMA expression associated with blood vessels or myofibroblasts. Endogenous peroxidases were quenched and 10% normal goat serum was used as a blocking agent. DAB/peroxide substrate was added for thirteen minutes. DAPI was applied to label nuclei. Cell nuclei associated with α-SMA and not with laminin were counted as myofibroblasts.
Myofibroblast numbers and percentage of total cells were significantly increased (t-test, p < 0.05) in the joint capsules of the patients when compared to organ donor control tissue. Total cell numbers were not significantly different in the patient and control tissue.
Modulators of α-SMA expression and myofibroblast formation include growth factors and matrix molecule components. Future work will look at the expression of these modulators in human elbow joint contractures.
Funding: Funding has not been received from a commercial party. This work was supported by The Alberta Heritage Foundation for Medical Research.
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Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
