Analysis of healing after myocardial infarction using polarized light microscopy

To better understand the healing process after permanent coronary artery occlusion in a canine model, the authors used polarized light microscopy. At 6 weeks after occlusion the scar collagen was mainly type I. Some regions of the scar contained a fiber lattice which appeared to be type III collagen. Collagen orientation was measured using a universal stage; subepicardial collagen was obliquely aligned (-14.0 +/- 3.5 degrees), midmyocardial collagen circumferentially aligned (1.4 +/- 0.4 degrees) and subendocardial collagen obliquely aligned (12.7 +/- 2.1 degrees). The molecular organization of scar collagen increased from 1 to 6 weeks after occlusion. Muscle cell disarray, similar to that in hypertrophic cardiomyopathy, was seen in the viable muscle adjacent to the scar. Such abnormal organization extended as far as 1 cm from the edge of the scar. The ability of polarized light microscopy to assess these different parameters from histologic sections demonstrates that it is a useful adjunct to other methods commonly used to study myocardial healing.

Glycosaminoglycan content in the media of cultured dermal fibroblasts derived from burn scar and normal skin

The glycosaminoglycan (GAG) content of the extracellular matrix of burn scar in humans has been reported to differ from that of normal skin. In order to investigate whether the GAG content altered as a result of functional changes in fibroblasts, the GAG content was determined in culture media of fibroblasts derived from growing burn scar, mature scar, and normal skin tissue. No statistical differences were observed in the population doubling-times of scar and normal skin. Mature scar showed significantly higher values for all the concentrations of uronic acid, hexosamine, and sulfate measured in the glycosaminoglycan, as compared with normal skin values, and the concentrations from growing scar were slightly higher than those for normal skin. The above results may suggest an increase in glycosaminoglycan sulfate synthesis following the hyperplasia of the matrix in burn scar tissue.

Effect of growth hormone and an anabolic steroid on hydroxyproline in healing dermal wounds in rats

Various fractions of hydroxyproline were determined in intact skin and in surgical dermal wounds of rats treated or not with one of two hormones: bovine growth hormone and anabolic steroid methandrostenolone. Serum hydroxyproline was also studied in these rats. Sampling was done prior to surgery, and at the end of the first and third weeks following operation. It was assumed that with the methods used, some information may be obtained regarding the synthesis and breakdown of collagen at early stage of wound healing. Presence of dermal wound was associated with significant increase of saline-extractable and total hydroxyproline in the skin distant from the healing wound. These fractions were also elevated in the scars. Growth hormone produced a significant increase in all extractable fractions and total hydroxyproline of both skin and scar. Serum hydroxyproline was also elevated in rats treated with growth hormone. These changes were considered due to the action of growth hormone on both synthesis and breakdown of collagen. The action of anabolic steroid on tissue hydroxyproline was generally comparable to that of growth hormone, but was much less marked. Methandrostenolone did not affect serum hydroxyproline content under the conditions of this experiment.