Bioactive hydrogels made from step-growth derived PEG-peptide macromers.

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Polymer Chemistry

Background:

• Synthetic poly(ethylene glycol) (PEG) hydrogels are vital biomaterials for cell biology and tissue engineering.
• Existing bioactive PEG hydrogels often require complex, expensive precursors.
• A need exists for simpler, more accessible PEG-based hydrogel systems.

Purpose of the Study:

• To develop a facile and cost-effective strategy for synthesizing bioactive poly(ethylene glycol) (PEG) hydrogels.
• To create tunable hydrogel microenvironments for studying cellular interactions and promoting angiogenesis.
• To investigate the impact of macromer molecular weight and matrix metalloproteinase (MMP) sensitivity on hydrogel properties and biological responses.

Main Methods:

• Step-growth polymerization of PEG diacrylate (PEGDA) with bis-cysteine MMP-sensitive peptides via Michael-type addition.
• Synthesis of cell-adhesive PEG-based macromers.
• Photopolymerization of macromers into hydrogels.
• Characterization of hydrogel swelling, degradation, and cell adhesion.
• Ex vivo aortic arch explant assay to assess angiogenesis and endothelial cell migration.

Main Results:

• High molecular weight (MW > 500 kDa) biodegradable photoactive macromers were synthesized using inexpensive PEG precursors.
• Resulting hydrogels exhibited increased swelling and collagenase-mediated degradation compared to existing systems.
• Immobilized cell-adhesive ligands (CGRGDS) were stable within the hydrogels.
• The hydrogel system successfully promoted angiogenesis and endothelial cell invasion in an ex vivo aortic arch assay.
• Capillary sprouting and cell migration were tunable by altering MMP-susceptibility and ligand presence.

Conclusions:

• The described facile chemistry provides a robust and versatile platform for creating tunable biomaterials.
• These novel PEG-based hydrogels effectively support angiogenesis and endothelial cell migration.
• The system offers significant potential for in vitro/ex vivo biological investigations and tissue engineering applications.
• This approach simplifies precursor sourcing, making advanced biomaterials more accessible.