Evaluation of ligament fibroblast viability in ruptured cranial cruciate ligament of dogs

Objective—To determine fibroblast viability, assess development of apoptosis, and evaluate tissue hypoxia via histochemical, in-situ hybridization, or immunohistochemical staining in ruptured and intact cranial cruciate ligaments (CCLs) of dogs. Animals—32 dogs with ruptured CCLs, and 8 aged and 19 young dogs with intact CCLs. Procedure—Markers of cell viability (lactate dehydrogenase [LDH]), apoptosis (terminal deoxynucleatidyl transferase-mediated deoxyuridine triphosphate-nick end labeling [TUNEL] method), and hypoxia (hypoxiainducible factor-1α [HIF-1α] monoclonal antibody) were applied to CCL specimens; positive cells were assessed objectively (LDH) and subjectively (TUNEL and HIF-1α) in the main axial tissue component (core) and synovial intima and subintima (epiligamentous tissue). Results—Viable fibroblasts were seen in all intact and ruptured CCLs. More nonviable cells were found in the core regions of ruptured CCLs and intact CCLs of young dogs than in the epiligamentous regions. Number of nonvi...