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Chronic wounds are an unmet clinical need affecting millions of patients globally, and current standards of care fail to consistently promote complete wound closure and prevent recurrence. Disruptions in growth factor signaling, a hallmark of chronic wounds, have led researchers to pursue growth factor therapies as potential supplements to standards of care. Initial studies delivering growth factors in protein form showed promise, with a few formulations reaching clinical trials and one obtaining clinical approval. However, protein‐form growth factors are limited by instability and off‐target effects. Gene therapy offers an alternative approach to deliver growth factors to the chronic wound environment, but safety concerns surrounding gene therapy as well as efficacy challenges in the gene delivery process have prevented clinical translation. Current growth factor delivery and gene therapy approaches have primarily used single growth factor formulations, but recent efforts have aimed to develop multi‐growth factor approaches that are better suited to address growth factor insufficiencies in the chronic wound environment, and these strategies have demonstrated improved efficacy in preclinical studies. This review provides an overview of chronic wound healing, emphasizing the need and potential for growth factor therapies. It includes a summary of current standards of care, recent advances in growth factor, cell‐based, and gene therapy approaches, and future perspectives for multi‐growth factor therapeutics.

 

Collagen-targeting strategies have proven to be an effective method for targeting drugs to pathological tissues for treatment of disease. The use of collagen-like peptides for controlling the assembly of drug delivery vehicles, as well as their integration into collagen-containing matrices, offers significant advantages for tuning the morphologies of assembled structures, their thermoresponsiveness, and the loading and release of both small-molecule and macro-molecular cargo. In this contribution, we summarize the design and development of collagen-peptide-based drug delivery systems introduced by the Kiick group and detail the expansion of our understanding and the application of these unique molecules through collaborations with experts in computational simulations (Jayaraman), osteoarthritis (Price), and gene delivery (Sullivan). Kiick was inducted as a Fellow of the National Academy of Inventors in 2019 and was to deliver an address describing the innovations of her research. Given the cancellation of the NAI Annual Meeting as a result of coronavirus travel restrictions, her work based on collagen-peptide-mediated assembly is instead summarized in this contribution. 

Compartments are a fundamental feature of life, based variously on lipid membranes, protein shells, or biopolymer phase separation. Here, this combines self‐assembling bacterial microcompartment (BMC) shell proteins and liquid‐liquid phase separation (LLPS) to develop new forms of compartmentalization. It is found that BMC shell proteins assemble at the liquid‐liquid interfaces between either 1) the dextran‐rich droplets and PEG‐rich continuous phase of a poly(ethyleneglycol)(PEG)/dextran aqueous two‐phase system, or 2) the polypeptide‐rich coacervate droplets and continuous dilute phase of a polylysine/polyaspartate complex coacervate system. Interfacial protein assemblies in the coacervate system are sensitive to the ratio of cationic to anionic polypeptides, consistent with electrostatically‐driven assembly. In both systems, interfacial protein assembly competes with aggregation, with protein concentration and polycation availability impacting coating. These two LLPS systems are then combined to form a three‐phase system wherein coacervate droplets are contained within dextran‐rich phase droplets. Interfacial localization of BMC hexameric shell proteins is tunable in a three‐phase system by changing the polyelectrolyte charge ratio. The tens‐of‐micron scale BMC shell protein‐coated droplets introduced here can accommodate bioactive cargo such as enzymes or RNA and represent a new synthetic cell strategy for organizing biomimetic functionality.