Enzymatically degradable alginate hydrogel systems to deliver endothelial progenitor cells for potential revasculature applications

Abstract

The objective of this study was to design an injectable biomaterial system that becomes porous in situ to deliver and control vascular progenitor cell release. Alginate hydrogels were loaded with outgrowth endothelial cells (OECs) and alginate lyase, an enzyme which cleaves alginate polymer chains. We postulated and confirmed that higher alginate lyase concentrations mediated loss of hydrogel mechanical properties. Hydrogels incorporating 5 and 50 mU/mL of alginate lyase experienced approximately 28% and 57% loss of mass as well as 81% and 91% reduction in storage modulus respectively after a week. Additionally, computational methods and mechanical analysis revealed that hydrogels with alginate lyase significantly increased in mesh size over time. Furthermore, alginate lyase was not found to inhibit OEC proliferation, viability or sprouting potential. Finally, alginate hydrogels incorporating OECs and alginate lyase promoted up to nearly a 10 fold increase in OEC migration in vitro than nondegradable hydrogels over the course of a week and increased functional vasculature in vivo via a chick chorioallantoic membrane (CAM) assay. Overall, these findings demonstrate that alginate lyase incorporated hydrogels can provide a simple and robust system to promote controlled outward cell migration into native tissue for potential therapeutic revascularization applications.

Open-source 3D printed air-jet for generating monodispersed alginate microhydrogels

“…By using the air-jet system with nitrogen gas in a nitrogen-enriched chamber, microbeads could be rapidly generated with anaerobic bacteria while displacing oxygen [21]. Furthermore, the use of enzymes to degrade alginate has been previously used to control the delivery of endothelial progenitor cells and adeno-associated vectors [46, 47]. The rapid degradation of microbeads observed here suggests heterogenous microbeads could result from a slower output rate, such as with microfluidic methods [28].…”

Biomaterial Based Strategies for Engineering New Lymphatic Vasculature

“…[23] These parameters can help guide selection of polymer materials to deliver lymphangiogenic therapeutics. Here we consider different properties of hydrogel applications utilizing controlled therapeutic release strategies to promote lymphangiogenesis ( [97][98][99] 2.0-3.0, Anionic [ 100] Nondegradable without modification: Hydrolysis [ 101] Enzymatic [ 97,[102][103][104] Food products [ 105] Dental applications [ 106] Wound dressing [ 107] Collagen 0.5-1.5 × 10 4 [ 108,109] 7.0-8.0, Neutral Biodegradable via collagenases [ 110] Cosmetics [ 106] Dental applications [ 106] Skin constructs [ 111] Repairing cartilage defects [ 112] Absorbable sutures [ 106] Vascular grafts [ 106] Fibrin 1.0-5.0 × 10 2 [ 113] 5.5-5.6, Anionic Biodegradable via Plasmin [ 114] Sealant [ 115] Gelatin 5-100 [ 116,117] Type A: 7.0-9.0, Neutral/cationic Type B: 4.7-5.2, anionic…”

“…An example of one such polymer is alginate, which is a naturally occurring anionic polysaccharide that has Food and Drug Administration (FDA) approval for food products, dental applications, and wound dressings and has a long history of supporting biomedical therapies. [105][106][107] Although alginate is biologically inert in mammals, alginate can be partially oxidized to allow for the polymer backbone to become susceptible to hydrolysis [140] and can be enzymatically degraded through the incorporation of exogenous alginate lyases [97] or polymer modification. [102][103][104] Alginate has many applications for delivering VEGF members due to these hydrogels being nanoporous [98,101,141] and having affinity for heparin binding proteins including basic fibroblast growth factor and VEGF-A.…”

“…These hydrogels often employ immobilized factors or control of mechanical properties including stiffness, crosslinking density, polymer orientation, or cell adhesion sites to direct cell or tissue growth ( Figure 5). [97,[153][154][155][156] In general, these hydrogel applications can allow for long term therapeutic stimulation via protecting immobilized factors from internalization or adjusting degradation rates to maintain desirable mechanical properties. [97,157,158] Hydrogels utilizing this strategy have applications for aligning, orienting and directing cell migration and driving stem cell differentiation to restore tissue function.…”

Recent Progress of Polysaccharide‐Based Hydrogel Interfaces for Wound Healing and Tissue Engineering

“…Hydrogels could be divided into natural hydrogels and synthetic ones according to the source of materials. In the natural hydrogels, the polymer networks are associated with the aqueous solvent inducing the swelling of crosslinkers and these binders are anchored by retractive force, ultimately the elasticity can totally neutralize the thermodynamic force of swelling . This “solid‐like fluid” polymers are linked by chemical or physical crosslinkers via the molecular chains .…”