PEGylated Platelet-Free Blood Plasma-Based Hydrogels for Full-Thickness Wound Regeneration

Abstract

Objective: To develop a cost-effective and clinically usable therapy to treat full-thickness skin injuries. We accomplished this by preparing a viscoelastic hydrogel using polyethylene glycol (PEG)-modified platelet-free plasma (PE-Gylated PFP) combined with human adipose-derived stem cells (ASCs). Approach: PEGylated PFP hydrogels were prepared by polymerizing the liquid mixture of PEG and PFP-ASCs and gelled either by adding calcium chloride (CaCl 2) or thrombin. Rheological and in vitro studies were performed to assess viscoelasticity and the ability of hydrogels to direct ASCs toward a vasculogenic phenotype, respectively. Finally, a pilot study evaluated the efficacy of hydrogels-ASCs using an athymic rat full-thickness skin wound model. Results: Hydrogels prepared within the range of 11 to 27 mM for CaCl 2 or 5 to 12.5 U/mL for thrombin exhibited a storage modulus of *62 to 87 Pa and *47 to 92 Pa, respectively. The PEGylated PFP hydrogels directed ASCs to form network-like structures resembling vasculature, with a fourfold increase in perivascular specific genes that were confirmed by immunofluorescent staining. Hydrogels combined with ASCs exhibited an increase in blood vessel density when applied to excisional rat wounds compared with those treated with hydrogels (110.3 vs. 95.6 BV/mm 2 ; p < 0.05). Furthermore, ASCs were identified in the perivascular region associated with newly forming blood vessels. Innovation: This study demonstrates that PFP modified with PEG along with ASCs can be used to prepare cost-effective stable hydrogels, at the bedside , to treat extensive skin wounds. Conclusion: These results indicate that PEGylated plasma-based hydrogels combined with ASCs may be a potential regenerative therapy for full-thickness skin wounds.

Effect of Fibrin Concentration on the In Vitro Production of Dermo-Epidermal Equivalents

“…Although PRP has shown its potency and capability in tissue regeneration, its experimental inconsistency and low reproducibility has meant that, in applications in which platelet-released growth factors are not crucial, PPP is generally used. Additionally, since PPP is cost-effective, suitable for bulk production, and easily translatable with minimal regulatory requirements for FDA approval, it is widely used in tissue regeneration [22,[40][41][42][43].…”

“…However, we found several persisting issues associated with the low final concentration of fibrin (1.2 mg/mL) used in the plasma derived-fibrin hydrogels when they are placed in transwell inserts for in vitro applications: (1) their height is reduced by 30% during the first 24 h and by 70% after 21 days in culture [17]; and (2) they suffer rapid degradation due to the skin cells present in the culture, limiting their lifespan (usually to 17 days) [15,44]. Several strategies have been proposed to overcome the limitations of plasma-derived fibrin-based hydrogels in skin tissue engineering, for example, combining fibrin (blood plasma-derived) with other molecules such as PEG or agarose polymers [40][41][42]50,51] or the use of highly concentrated commercial fibrinogen. In our experience, the use of commercial fibrinogen in organotypic skin cultures produced worse keratinocyte proliferative and differentiation behavior in comparison with PPP-hydrogel cultures.…”

Contraction of fibrin‐derived matrices and its implications for in vitro human skin bioengineering

“…Several attempts such as physical modification, anchoring the hydrogels, caging in solid scaffolds, chemical modification or even introducing other synthetic or natural polymers, have been made to overcome the contractility of collagen and fibrin hydrogels in skin tissue engineering (Braziulis et al, 2012; Burmeister et al, 2016; Burmeister, Roy, Becerra, Natesan, & Christy, 2018; Lotz et al, 2017; Mandrycky, Wang, Kim, & Kim, 2016; Monaghan, Browne, Schenke‐Layland, & Pandit, 2014; Mori, Morimoto, & Takeuchi, 2017; Natesan et al, 2019; Sriram et al, 2018; Stone, Wall, Natesan, & Christy, 2018). In all these studies, it was considered that fibroblasts‐mediated matrix contraction is the main component of this phenomenon (de Jesus & Sander, 2014; Freyman, Yannas, Yokoo, & Gibson, 2001; Grinnell, 2000; Jansen, Bacabac, Piechocka, & Koenderink, 2013; Tuan et al, 1996; Zhu et al, 2001).…”

Clinical Translational Potential in Skin Wound Regeneration for Adipose-Derived, Blood-Derived, and Cellulose Materials: Cells, Exosomes, and Hydrogels

“…Investigators at the U.S. Army Institute of Surgical Research have used polyethylene glycol (PEG) modification chemistry to adapt fibrin hydrogels prepared from purified fibrin and thrombin or from platelet-rich plasma as therapeutics for burns and full-thickness skin wound models [ 90 , 91 , 92 , 93 , 94 , 95 ]. These materials can be applied topically following creation of the lesion to enhance healing.…”