Induced elastic matrix deposition within three-dimensional collagen scaffolds

Area of Science:

• Biomaterials Science
• Vascular Biology
• Tissue Engineering

Background:

• Vascular homeostasis relies on elastic matrix integrity, primarily elastin, maintained by vascular smooth muscle cells (SMCs).
• Degradation of elastic matrix in vascular diseases and limited elastin regeneration by adult SMCs impair vascular health.
• Tissue engineering of elastic structures is hindered by the inability to induce adult cells to synthesize and organize tropoelastin into functional matrices, especially in collagen-rich environments.

Purpose of the Study:

• To investigate the synergistic effects of transforming growth factor-beta1 (TGF-β1) and hyaluronan oligomers (HA-o) on elastic matrix deposition by adult rat aortic SMCs (RASMCs).
• To assess the impact of TGF-β1 and HA-o on tropoelastin production, elastin crosslinking, and matrix metalloproteinase (MMP) activity in a collagenous scaffold.
• To evaluate the potential of these factors in promoting elastogenesis within engineered vascular constructs.

Main Methods:

• Adult rat aortic SMCs (RASMCs) were seeded in non-elastogenic, type-I collagen gels under static load.
• Cultures were treated with varying doses of TGF-β1 and HA-o.
• Elastin deposition, tropoelastin production, lysyl-oxidase, MMP-2 and MMP-9 levels, and elastic fiber organization were analyzed over 3 weeks.
• Von Kossa staining was used to detect calcification.

Main Results:

• TGF-β1 and HA-o synergistically enhanced matrix elastin deposition, particularly soluble elastin at lower doses and insoluble elastin at higher doses.
• Elevated lysyl-oxidase protein levels correlated with increased insoluble elastin at higher factor concentrations.
• While tropoelastin production did not significantly increase, TGF-β1 and HA-o reduced MMP-9 activity and, at higher TGF-β1 doses, MMP-2 activity.
• Elastic fibers were discontinuous within the collagen constructs, and no calcification was observed.

Conclusions:

• TGF-β1 and HA-o demonstrate a beneficial effect in inducing matrix elastin synthesis by adult RASMCs within a collagen-rich environment.
• These factors show potential for enhancing elastogenesis in tissue-engineered vascular constructs, despite limitations in tropoelastin synthesis and elastic fiber organization.
• Further optimization is needed to improve overall matrix yield and achieve more continuous elastic fiber formation for robust vascular tissue engineering.