HISTOLOGIC ASSESSMENT OF TISSUE HEALING OF HYALINE CARTILAGE BY USE OF SEMIQUANTITATIVE EVALUATION SCALE

Kao avaskularno, alimfatično i aneuralno tkivo sa smanjenom mogućnošću cijeljenja, hijalina hrskavica je zanimljiv predmet istraživanja. Ispitivane su brojne metode kojima bi se potakla regeneracija oštećene hrskavice no niti jedna od njih ne daje idealne rezultate. Rezultate spomenutih metoda potrebno je odgovarajuće ocijeniti. Cilj ove studije bio je analizirati rezultate dobivene primjenom ugrušaka autologne koštane srži prethodno transduciranih faktorom rasta TGF-β1 na oštećenja zglobne hrskavice. Istraživanje je provedeno na 28 koštano zrelih ovaca koje su slučajnim odabirom podijeljene u 4 skupine te im je kirurški učinjeno oštećenje zglobne hrskavice na nosivoj površini medijalnog kondila bedrene kosti. U oštećenje je zatim ansplantiran autologni ugrušak koštane srži transduciran faktorom rasta - TGF-β1 (skupina TGF), zelenim fluorescentnim proteinom - GFP (skupina GFP), bez genetske promjene (skupina BM) ili nije postavljen nikakav transplantat (skupina NC). Uzorci su pregledani pomoću svjetlosnog kroskopa i ocijenjeni primjenom vizualno-histološke ocjenske ljestvice Međunarodnog društva za istraživanje hrskavice (ICRS-a). Statistička analiza pokazala je značajnu razliku između skupine TGF i NC. Rezultati pokazuju da je primjenom ove ljestvice moguće dobiti mjerljive histološke rezultate.Introduction: Articular cartilage is an avascular and aneural tissue lacking lymph drainage, hence its inability of spontaneous repair following injury. Thus, it offers an interesting model for scientific research. A number of methods have been suggested to enhance cartilage repair, but none has yet produced significant success. The possible application of the aforementioned methods has brought about the necessity to evaluate their results. The objective of this study was to analyze results of a study of the effects of the use of TGF-β gene transduced bone marrow clot on articular cartilage defects using ICRS visual histological assessment scale. Methods: The research was conducted on 28 skeletally mature sheep that were randomly assigned to four groups and surgically inflicted femoral chondral defects. The articular surfaces were then treated with TGF-β1 gene transduced bone marrow clot (TGF group), GFP transduced bone marrow clot (GFP group), untransduced bone marrow clot (BM group) or left untreated (NC group). The analysis was performed by visual examination of cartilage samples and results were obtained using ICRS visual histological assessment scale. The results were subsequently subjected to statistical assessment using Kruskal-Wallis and Mann-Whitney tests. Results: Kruskal-Wallis test yielded statistically significant difference with respect to cell distribution. Mann-Whitney test showed statistically significant difference between TGF and NC groups (P=0.002), as well as between BM and NC groups (P=0.002 with Bonferroni correction). Discussion: Twenty-six of the twenty-eight samples were subjected to histologic and subsequent statistical analysis; two were discarded due to faulty histology technique. Our results indicated a level of certainty as to the positive effect of TGF-β1 gene transduced bone marrow clot in restoration of articular cartilage defects. However, additional research is necessary in the field. One of the significant drawbacks on histologic assessment of cartilage samples were the errors in histologic preparation, for which some samples had to be discarded and significantly impaired the analytical quality of the others. Defects of structures surrounding the articular cartilage, e.g., subchondral bone or connective tissue, might also impair the quality of histologic analysis. Additional analyses, i.e. polarizing microscopy should be performed to determine the degree of integration of the newly formed tissue with the surrounding cartilage. The semiquantitative ICRS scale, although of great practical value, has limitations as to the objectivity of the assessment, taking into account the analytical ability of the evaluator, as well as the accuracy of emiquantitative analysis in comparison to the methods of quantitative analysis.Conclusion: Overall results of histologic analysis indicated that the application of TGF-β1 gene transduced bone marrow clot could have measurable clinical effects on articular cartilage repair. The ICRS visual histological assessment scale is a valuable analytical method for cartilage repair evaluation. In this respect, further analyses of the method value would be of great importance