Mechanobiological modulation: physiological pressure preconditioning boosts the paracrine-driven lymphangiogenic capacity of bone marrow mesenchymal stem cells.

INTRODUCTION: Lymphatic system remodeling and regeneration are essential for tissue repair and homeostasis, and these processes are precisely regulated by both biochemical and biomechanical signals in the tissue microenvironment. The mechanobiological mechanisms governing this process remain largely elusive, particularly in oral and maxillofacial tissues which are constantly exposed to complex mechanical forces. Bone marrow mesenchymal stem cells (BMSCs) hold great promise for regenerative medicine due to their robust paracrine activity, but how mechanical preconditioning modulates their pro-lymphangiogenic paracrine effects has not been systematically investigated. METHODS: Primary rat BMSCs were isolated and characterized, then subjected to mechanical pressure to collect pressure-preconditioned conditioned medium (P-B-CM). Conditioned medium harvested from untreated, routinely cultured BMSCs served as B-CM. Commercially acquired primary lymphatic endothelial cells (LECs) were validated with lymphatic-specific markers, then cultured in B-CM or P-B-CM to assess intergroup functional differences. Proliferation was quantified via CCK-8 and cell cycle assays; migration was examined by wound healing tests and cytoskeleton staining. Transwell permeability assays, VE-cadherin staining, and transmission electron microscopy were used to evaluate barrier integrity. An in vitro tube formation assay and ex vivo thoracic duct culture further measured the lymphangiogenic capacity of LECs cultured with different conditioned media. RESULTS: Compared with the control B-CM group, LECs cultured with P-B-CM exhibited accelerated cell cycle progression and improved cytoskeleton remodeling. Transwell permeability detection, VE-cadherin immunostaining, and TEM observations collectively demonstrated that P-B-CM strengthened intercellular barrier integrity by increasing the length of continuous adherens junctions. Consistent with the in vitro cellular findings, ex vivo rat thoracic duct culture further verified that P-B-CM induced more robust lymphatic sprouting, confirming its promotive effects on lymphangiogenesis. CONCLUSION: Mechanical pressure preconditioning enhances the pro-lymphangiogenic paracrine activity of BMSCs, optimizes LEC barrier function and lymphatic sprouting, and offers a biomechanical strategy for oromaxillofacial lymphatic regeneration.