Bioengineered M13 Bacteriophage–GelMA Construct Modulates Immune Responses in a Preclinical Model of Sepsis

A life-threatening condition, sepsis is defined by dysregulated immune system responses and multi-organ dysfunction. There is still no drug or treatment that can completely and guarantee to cure this condition; available treatments mainly focus on controlling the infection with antibiotics, supporting organ function, and managing symptoms. Although artificial lymphoid tissues (ALTs) have potential for localized immunomodulation, their application is often limited by inadequate biological function and poor structural integrity. To address these issues, we developed a novel bioink that combines gelatin methacryloyl (GelMA) with M13 bacteriophage, a filamentous, non-lytic virus recognized for its immunomodulatory activity, self-assembling capacity, and biocompatibility. Male C57BL/6 mice (8-10 weeks, 22-25 g) were randomly assigned to six groups: sham + normal saline (NS), CLP + NS, CLP + M13, 3D-M13, 3D+M13, and 3D+M13 + CLP. The cecal ligation and puncture (CLP) procedure was applied to induce polymicrobial sepsis. Cell-laden, three-dimensional (3D) bioprinted GelMA scaffolds with or without M13 bacteriophage were surgically implanted on the spleen 35 days prior to sepsis induction. Subsequently, immune, histological, and biochemical parameters were assessed. Compared with GelMA-only scaffolds, M13-containing scaffolds demonstrated improved printability, mechanical stability, cellularity, and angiogenesis. Mice implanted with 3D+M13 scaffolds exhibited significantly reduced levels of pro-inflammatory cytokines, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), as well as higher levels of anti-inflammatory cytokines interleukin-10 (IL-10) and transforming growth factor beta (TGF-β). Additionally, the bacterial load was reduced, and organ injury in the liver, lungs, and kidneys was reduced. Circulating liver enzyme levels were also reduced, suggesting precautionary measures against sepsis-induced hepatic dysfunction. The integration of M13 bacteriophage into GelMA bioink is a distinctive approach that simultaneously enhances the stability of ALT and stimulates anti-inflammatory immune modulation. This dual structural-immunological effect defines a new paradigm for the development of multifunctional biomaterials in the fields of immune regulation and tissue engineering.