Effect of Autologous Platelet-Rich Plasma and Gelatin Sponge for Tendon-to-Bone Healing After Rabbit Anterior Cruciate Ligament Reconstruction

Abstract

To investigate platelet-rich plasma (PRP) combined with gelatin sponge (GS) to improve tendon-bone interface healing and structure formation. Characterization of the GS scaffold was performed with a scanning electron microscope, and the release curve after loading with PRP was evaluated. A real-time reverse transcription quantitative polymerase chain reaction assay was performed to test the levels of tendon-to-bone healing-related gene expression. Finally, 18 New Zealand white rabbits were randomly divided into 3 groups and underwent semitendinosus autograft anterior cruciate ligament reconstruction: autograft group without PRP, PRP group, and PRP-GS group. All rabbits were killed 8weeks after the operation. Magnetic resonance imaging scans, biomechanical testing, and histologic evaluation were performed. An enzyme-linked immunosorbent assay and cell counting kit-8 assay showed that the GS could control the release of PRP and prolong its bioactivity time, as well as promote bone marrow mesenchymal stem cell proliferation. In the PRP-GS group, the levels of related genes were upregulated compared with the PRP group (P < .05). Lower signal in the magnetic resonance images indicated fibrocartilage formation in the 2 groups with PRP. In addition, histologic staining showed that the tendon-bone connection had a greater fibrocartilaginous transition region in the PRP-GS group, and the histologic scores were higher (vs the PRP group, P= .039). The maximum failure load and stiffness were higher in the PRP-GS group than in the other 2 groups. GS loading with PRP could prolong the bioactivity time of PRP and promote bone marrow mesenchymal stem cell proliferation and osteogenic gene expression invitro. It also promoted the early healing process at the tendon-bone junction in a rabbit anterior cruciate ligament reconstruction model. GS is a natural material and offers satisfactory biocompatibility. Using GS as a scaffold to control the release of bioactive factors in bone tunnels may be useful, but additional studies in human subjects will be necessary to evaluate its clinical prospects.