MATRIX VESICLES AND CULTURE MEDIA VESICLE (EXOSOME): A COMPARATIVE STUDY OF GROWTH PLATE MINERALIZATION AND ECTOPIC CALCIFICATION

Pathological calcification of soft tissues is a hallmark of several major diseases, such as cardiovascular abnormalities and osteoarthritis. It has been described that the formation of macrocalcifications in pathological conditions shares common features with endochondral ossification of long bones. The initiation and progression of pathological calcifications have been related to the transdifferentiation of resident cells from a specific soft tissue into chondrocyte-like cells, which become hypertrophic after maturation. During (patho)physiological calcifications, mineralizing phenotype cells release a special class of matrix-bound extracellular vesicles (EV), also named matrix vesicles (MV), which are responsible for the deposition of biological apatite on the extracellular matrix. Although it has been described that the MVs’ membrane proteins are located and pre-arranged in the microvilli from the parent cells, proteomic analyses have revealed that part of these proteins do not originate from the microvilli, suggesting the existence of a protein corona heritage from the surrounding. In this study, it has been investigated the role of this protein corona in modulating the MVs' mineralization capacity, as well as its influence in binding the MV to collagen fibrils. Thus, MV were isolated from the murine vascular smooth muscle cell line (MOVAS) and compared with vesicles obtained from chondrocytes. MVs' protein corona was removed using a high-ionic-strength buffer, the generated MV were named SMV. The results obtained showed a distinct protein profile between MV and SMV, corroborating, through the modulation of Tissue-nonspecific alkaline phosphatase (TNAP) activity and turbidimetry assays, the loss of SMVs’ mineralization capacity. Taken together, the results indicate that the MVs’ protein corona affects their functionality. This approach offers a versatile two-cell model platform for studying pathological calcification and developing therapeutic agents through understanding hypertrophic chondrocyte behavior and regulation.
This work was supported by CNPq (151671/2022-2; 305426/2021-4) and FAPESP (2024/12254-1; 2019/08568-2).