Increasing salinity of fibrinogen solvent generates stable fibrin hydrogels for cell delivery or tissue engineering

Abstract

Fibrin has been used clinically for wound coverings, surgical glues, and cell delivery because of its affordability, cytocompatibility, and ability to modulate angiogenesis and inflammation. However, its rapid degradation rate has limited its usefulness as a scaffold for 3D cell culture and tissue engineering. Previous studies have sought to slow the degradation rate of fibrin with the addition of proteolysis inhibitors or synthetic crosslinkers that require multiple functionalization or polymerization steps. These strategies are difficult to implement in vivo and introduce increased complexity, both of which hinder the use of fibrin in research and medicine. Previously, we demonstrated that additional crosslinking of fibrin gels using bifunctionalized poly(ethylene glycol)-n-hydroxysuccinimide (PEG-NHS) slows the degradation rate of fibrin. In this study, we aimed to further improve the longevity of these PEG-fibrin gels such that they could be used for tissue engineering in vitro or in situ without the need for proteolysis inhibitors. It is well documented that increasing the salinity of fibrin precursor solutions affects the resulting gel morphology. Here, we investigated whether this altered morphology influences the fibrin degradation rate. Increasing the final sodium chloride (NaCl) concentration from 145 mM (physiologic level) to 250 mM resulted in fine, transparent high-salt (HS) fibrin gels that degrade 2–3 times slower than coarse, opaque physiologic-salt (PS) fibrin gels both in vitro (when treated with proteases and when seeded with amniotic fluid stem cells) and in vivo (when injected subcutaneously into mice). Increased salt concentrations did not affect the viability of encapsulated cells, the ability of encapsulated endothelial cells to form rudimentary capillary networks, or the ability of the gels to maintain induced pluripotent stem cells. Finally, when implanted subcutaneously, PS gels degraded completely within one week while HS gels remained stable and maintained viability of seeded dermal fibroblasts. To our knowledge, this is the simplest method reported for the fabrication of fibrin gels with tunable degradation properties and will be useful for implementing fibrin gels in a wide range of research and clinical applications.

The degradation of gelatin/alginate/fibrin hydrogels is cell type dependent and can be modulated by targeting fibrinolysis

“…We have tested broad inhibitor for MMP and serine proteases, however, we did not evaluate the activity of proteases in the supernatant, nor the effect of addition to FCS to the medium in terms on addition of proteases or their possible excess compared to inhibitors quantities. Similar results were obtained by Jarrell et al (2021) who demonstrated that increasing sodium chloride concentrations up to 250 mM, i.e., hyperosmotic, instead of 150mM, i.e., a physiological concentration, led to transparent fibrin gel formation degrading two to three times slower than controls. However, two limitations were foreseen in the study by Jarrell et al (2021) when considering to apply this protocol to cell-laden hydrogels.…”

“…Similar results were obtained by Jarrell et al (2021) who demonstrated that increasing sodium chloride concentrations up to 250 mM, i.e., hyperosmotic, instead of 150mM, i.e., a physiological concentration, led to transparent fibrin gel formation degrading two to three times slower than controls. However, two limitations were foreseen in the study by Jarrell et al (2021) when considering to apply this protocol to cell-laden hydrogels. First, hyperosmolar culture media or buffers can cause an osmotic shock leading to a rapid cell shrinkage and associated cell death.…”

A defined heat pretreatment of gelatin enables control of hydrolytic stability, stiffness, and microstructural architecture of fibrin–gelatin hydrogel blends

“…Previous studies show that this can be reduced by tuning the delicate equilibrium of pH and calcium and thrombin concentration, respectively, or by addition of protease inhibitiors such as aprotinin, aminocaproic acid and tranexamic acid, which enhance the stability of the fibrin clot. 46–51 In combination with gelatin, stable hydrogel blends can be achieved, however with high swelling ratios at high gelatin concentrations. This study shows improved processing of low concentrated and open-porous fibrin-based hydrogels with great long-term stability, which can be of great advantage for tissue engineering applications.…”

Sensing Alzheimer’s Disease Utilizing Au Electrode by Controlling Nanorestructuring

“…PEGylation can increase solubility and stability and reduce immunogenicity of peptides and proteins. A similar procedure has been reported before for the immobilization of α-synuclein (αS) protein on a gold surface in near-field effect detection [45,46]. The detection of Aβ protein and corresponding CV analysis for the detection of 10 −2 to 10 6 pg/mL is displayed in Figure 5.…”