Cartilage tissue has a limited capacity for healing with the consequence that patients are often treated symptomatically until they become candidates for osteotomy or total joint replacement. Alternative biological therapies, for example, application of platelet-rich plasma and implantation of chondrocytes and mesenchymal stem cells, have emerged as a new treatment modality to repair articular cartilage. In addition, autologous fat transfer is performed for treatment of cartilage defects, example given, in osteoarthrosis, but several questions regarding basic biochemical properties of the transplant remain unanswered. Bone morphogenetic protein 4 (BMP4), matrix metalloproteinase (MMP)-8, cartilage oligomeric matrix protein (COMP), and chitinase-3-like protein 1 (CHI3L1) have been shown to be involved in chondrogenic regeneration and represent potential therapeutic agents for cartilage repair. However, no study regarding naturally occurring levels of these soluble factors in transplanted adipose tissue has yet been performed.
To investigate the influence of age, body mass index, donor site, and sex on the concentration of BMP4, MMP-8, COMP, and CHI3L1 in freshly aspirated adipose tissue, their content was measured by means of enzyme-linked immunosorbent assay readings.
There were significant quantities of BMP4, MMP-8, COMP, and CHI3L1 (23.6, 249.9, 298.0, and 540.6 pg/mg, respectively) in the lipoaspirate harvested for transplantation. There was no correlation between the content of soluble factors and the patients' age or body mass index. Furthermore, the sex did not affect the amount of the investigated factors. However, there were significantly lower contents of BMP4, COMP, and CHI3L1 found in lipoaspirates harvested from the abdomen compared with nonabdominal donor sites.
Naturally occurring differences in the concentrations of the investigated soluble factors will favor certain donor sites for autologous fat transfer in the field of cartilage repair. Thus, increasing knowledge will enable researchers and clinicians to make autologous fat transfer procedures more reliable and efficient for treatment of articular cartilage defects.
From the Department of Plastic Surgery, Hand Surgery–Burn Center University Hospital RWTH Aachen, Aachen, Germany.
Received November 16, 2018, and accepted for publication, after revision February 18, 2019.
T.R. and J.P.S. equally contributing authors.
Conflicts of interest and sources of funding: This research did not receive any specific grant from following organizations: National Institutes of Health, WellcomeTrust, Howard Hughes Medical Institute, Research Councils UK, and other(s). The authors declare no conflict of interest.
This study was supported by “START,” a program for young scientists of the Medical Faculty at the RWTH University Aachen.
Reprints: Tim Ruhl, PhD, Department of Plastic Surgery, Hand Surgery–Burn Center, University Hospital RWTH Aachen Pauwelsstraße 30, 52074 Aachen, Germany. E-mail: email@example.com.