Characterization of Chemically Modified Human Amniotic Membranes for Tissue Engineering Applications
Abstract
The human amniotic membrane (hAM) is a collagen-based extracellular matrix derived from the human placenta. It is a readily-available, inexpensive, and naturally biocompatible material. Despite its attractive biological and biochemical properties, the hAM has been restricted for some tissue engineering or regenerative medicine applications by its moderate mechanical properties and rapid biodegradation. In this work, the use of riboflavin, a water-soluble vitamin, is investigated to crosslink and strengthen the human amniotic membrane under UVA light. The effect of riboflavin-UVA crosslinking on hAM properties were determined via infrared spectroscopy, uniaxial tensile testing, proteolytic degradation, permeability testing, SEM, and quantification of free (un-crosslinked) amine groups. Improved hAM mechanical properties must not come at the expense of reduced cellular proliferation and induction capabilities. In this study were assessed the viability, proliferation, immunophenotype, and multilineage differentiation ability of human adipose-derived stem cells seeded on riboflavin-UVA crosslinked membranes. Overall, hAM crosslinked with riboflavin-UVA benefited from a stable 2.5-fold increase in mechanical properties and improved biodegradation, all while retaining their biocompatibility and abilities to support the cultivation and differentiation of adipose-derived stem cells. Together, these results suggest that riboflavin-UVA crosslinking is an effective strategy to enhance the hAM for potential cardiovascular and tendon tissue engineering applications. Additionally, porcine adipose-derived stem cells (pASCs) were identified as a reliable stem cell source thanks to their abundance, straightforward isolation, and broad differentiation abilities. Knowledge of the properties of pASCs is critical for the success of therapeutic studies in preclinical pig models. Finally, the construction of a simple mechanical testing apparatus using off-the-shelf materials and open-source software for a total cost of less than $100 is reported.
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