The implantation of a biomaterial quickly initiates a tissue repair program initially characterized by a neutrophil influx. During the acute inflammatory response, neutrophils release neutrophil extracellular traps (NETs) and secrete soluble signals to modulate the tissue environment. In this work, we evaluated chloroquine diphosphate, an antimalarial with immunomodulatory and antithrombotic effects, as an electrospun biomaterial additive to regulate neutrophil-mediated inflammation. Electrospinning of polydioxanone was optimized for rapid chloroquine elution within 1 h, and acute neutrophil-biomaterial interactions were evaluated in vitro with fresh human peripheral blood neutrophils at 3 and 6 h before quantifying the release of NETs and secretion of inflammatory and regenerative factors. Our results indicate that chloroquine suppresses NET release in a biomaterial surface area–dependent manner at the early time point, whereas it modulates signal secretion at both early and late time points. More specifically, chloroquine elution down-regulates interleukin 8 (IL-8) and matrix metalloproteinase nine secretion while up-regulating hepatocyte growth factor, vascular endothelial growth factor A, and IL-22 secretion, suggesting a potential shift toward a resolving neutrophil phenotype. Our novel repurposing of chloroquine as a biomaterial additive may therefore have synergistic, immunomodulatory effects that are advantageous for biomaterial-guided in situ tissue regeneration applications.

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Electrospun biomaterials for in situ tissue regeneration are advantageous as drug delivery systems because they can be used to regulate the acute inflammatory response to establish a regenerative microenvironment. Neutrophils are the first inflammatory cells recruited to an electrospun biomaterial, and their release of neutrophil extracellular traps (NETs) and secretion of inflammatory and regenerative signals modulate the microenvironment around the biomaterial. In this work, chloroquine diphosphate, an anti-inflammatory drug shown to decrease NET release, was electrospun into polydioxanone (PDO) fibers for local delivery and immunomodulation of biomaterial-interacting neutrophils. Electrospinning was optimized so that the eluted concentration of chloroquine reached a previously reported, therapeutic concentration of 10 µM within one hour. Subsequently, acute neutrophil–template interactions were evaluated in vitro with freshly isolated human peripheral blood neutrophils for 3 and 6 h. NET release was quantified through detection of NET-derived myeloperoxidase with an ELISA, and the secretion of inflammatory and regenerative factors was quantified with an immunomagnetic multiplex assay. The results indicate that the chloroquine-eluting templates significantly reduced NET release within the first 3 h, but had no effect at 6 h, suggesting a therapeutic window for modulating acute NET release or temporal changes in cell viability. Additionally, the elution of chloroquine increased the secretion of regenerative factors HGF, VEGF-A, and IL-22 while suppressing inflammatory signals MMP-9 and IL-8 at 3 and 6 h, indicating a shift towards a pro-healing neutrophil phenotype. Together, these data suggest that chloroquine-eluting PDO biomaterials may modulate the acute neutrophil response from inflammatory to pro-healing, which may significantly enhance in situ tissue regeneration. Future work includes in vivo studies to evaluate long-term effects on tissue integration and regeneration in a physiological environment. Ultimately, these electrospun biomaterials may function as immunomodulatory drug delivery systems that regulate the neutrophil response and enhance the potential for in situ tissue regeneration.

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