Development of alginate and alginate sulfate/polycaprolactone nanoparticles for growth factor delivery in wound healing therapy

Connective tissue growth factor (CTGF) holds great promise for enhancing the wound healing process; however, its clinical application is hindered by its low stability and the challenge of maintaining its effective concentration at the wound site. Herein, we developed novel double-emulsion alginate (Alg) and heparin-mimetic alginate sulfate (AlgSulf)/polycaprolactone (PCL) nanoparticles (NPs) for controlled CTGF delivery to promote accelerated wound healing. The NPs' physicochemical properties, cytocompatibility, and wound healing activity were assessed on immortalized human keratinocytes (HaCaT), primary human dermal fibroblasts (HDF), and a murine cutaneous wound model. The synthesized NPs had a minimum hydrodynamic size of 200.25 nm. Treatment of HaCaT and HDF cells with Alg and AlgSulf2.0/PCL NPs did not show any toxicity when used at concentrations <50 µg/mL for up to 72 h. Moreover, the NPs' size was not affected by elevated temperatures, acidic pH, or the presence of a protein-rich medium. The NPs have slow lysozyme-mediated degradation implying that they have an extended tissue retention time. Furthermore, we found that treatment of HaCaT and HDF cells with CTGF-loaded Alg and AlgSulf2.0/PCL NPs, respectively, induced rapid cell migration (76.12% and 79.49%, P<0.05). Finally, in vivo studies showed that CTGF-loaded Alg and AlgSulf2.0/PCL NPs result in the fastest and highest wound closure at the early and late stages of wound healing, respectively (36.49%, P<0.001 on day 1; 90.45%, P<0.05 on day 10), outperforming free CTGF. Double-emulsion NPs based on Alg or AlgSulf represent a viable strategy for delivering heparin-binding GF and other therapeutics, potentially aiding various disease treatments.