Use of Bone Marrow Stromal Cells for Tendon Graft-to-bone Healing: Histological and Immunohistochemical Studies in a Rabbit Model

Background: Despite increasing attention on the issue of tendon-to-bone integration, there has been no animal study on the use of cell therapy for promoting the insertion healing of tendon to bone.

Purpose: To determine the efficacy of using a large number of bone marrow stromal cells (bMSCs) to enhance tendon-to-bone healing.

Study Design: Controlled laboratory study.

Methods: The hallucis longus tendons were translated into 2.5-mm diameter calcaneal bone tunnels in a New Zealand white rabbit model. The bone tunnels were treated with or without bMSCs. Three specimens from each group were harvested at 2, 4, and 6 weeks postoperatively and evaluated by conventional histological and immunohistochemical methods.

Results: At 4 weeks, the specimens with bMSCs exhibited more perpendicular collagen fiber formation and increased proliferation of cartilage-like cells, which was indicated by positive collagen type-II immuno-staining of the tendon-bone interface. In contrast, the specimens without bMSCs demonstrated progressive maturation and reorganization of fibrous tissue aligned along the load axis.

Conclusion: Introduction of a large number of bone marrow stromal cells to the bone tunnel have shown to improve the insertion healing of tendon to bone in a rabbit model through formation of fibrocartilagenous attachment at early time points.