(P 29) Angiogenic Potential of the Early Fracture Haematoma Is Increased By Mechanical Stimulation

• Published in: Tissue engineering. Part A Vol. 14; no. 5; p. 807
• Main Authors: Groothuis, A, Kasper, G, Lehnigk, U, Bail, H, van Scherpenzeel, K, Duda, G
• Format: Journal Article
• Language: English
• Published: 01.05.2008
• ISSN: 1937-3341; 1937-335X

Mechanical stimulation and angiogenesis play important roles in the bone healing process. The increased secretion of matrix metalloproteases (MMPs) and paracrine stimulation of angiogenesis by mechanical loading of mesenchymal stem cells have been described earlier. However, the exact interaction of angiogenesis and mechanical loading remains unclear. This study aimed to investigate the angiogenic potential of the human fracture haematoma itself and how this changes with mechanical stimulation, as well as identify molecules potentially involved. Fracture haematomas were isolated during surgery max. 24 hours post-trauma. They were embedded in a fibrin matrix and mechanically stimulated in a bioreactor simulating the in vivo-conditions in the early phase of bone healing (3 days, 1 Hz, 10 kPa). Both MMP-2 active and proform and MMP-9 proform were detected in haematomas by gelatine zymography. In vitro angiogenesis assays of endothelial cells (HMEC-1) showed increased tube formation when stimulated with conditioned medium from mechanically stimulated haematoma. Proliferation of HMEC-1 cells stimulated by haematoma suggests the presence of stimulatory molecules. In summary, extracellular, pro-angiogenic MMPs are present in the early human fracture haematoma and mechanical loading appears to enhance its pro-angiogenic potential. Their regulation could be a bridge between mechanical stimulation and angiogenesis. Such link would open new therapeutic strategies in bone healing process by stimulating blood vessels formation.