Russell, C. R. | Search bioRxiv

bioRxiv2026

Avidity-controlled biotherapeutic delivery systems for the treatment of ischemia-reperfusion acute kidney injury

Regulatory T cells (Tregs) are key mediators of immune resolution and tissue repair following acute kidney injury (AKI), yet strategies to selectively enrich Tregs within the renal microenvironment remain limited. Interleukin-2 (IL-2) is essential for Treg survival and function, but systemic IL-2 delivery is constrained by a short half-life, narrow therapeutic window, and risk of off-target activation of cytotoxic T cells. Effective Treg-based immunomodulation may therefore require both localized cytokine signaling and targeted recruitment of precursor immune populations. Here, we present a sequential, biomaterial-based immunomodulatory strategy that integrates immune cell recruitment with sustained cytokine delivery. An injectable granular hydrogel physically encapsulating the chemokine CCL21 was used to initially recruit CD4+ T cells to the injured kidney. Subsequently, supramolecular guest-host interactions were leveraged to deliver IL-2 modified with the hydrophobic "guest" moiety adamantane, enabling prolonged local cytokine release over 28 days. In healthy mice, we observed early CD4+ T cell recruitment, followed by a pronounced increase in Treg frequency, consistent with immune reprogramming driven by our sequential delivery system. In a murine model of bilateral ischemia-reperfusion (BiAKI), this injectable biomaterial induced a local increase in the proportion of FOXP3-expressing Tregs and a concomitant decrease in the levels of AKI markers. This two-step immunomodulatory approach minimizes acute immune activation while promoting long-term enrichment of Tregs within the renal microenvironment. Together, these findings demonstrate that granular hydrogels with supramolecular host capability can orchestrate immune recruitment and differentiation in a spatiotemporally controlled manner, providing a versatile immunomodulatory platform for applicability in kidney disease.

bioengineering↗

bioRxiv2021

Gain-of-function cardiomyopathic mutations in RBM20 rewire splicing regulation and re-distribute ribonucleoprotein aggregates within processing bodies

RNA binding motif protein 20 (RBM20) is a key regulator of alternative splicing in the heart, and its mutation leads to malignant dilated cardiomyopathy (DCM). To understand the mechanism of RBM20-associated DCM, we engineered isogenic human induced pluripotent stem cells (iPSCs) with heterozygous or homozygous DCM-associated missense mutations in RBM20 (R636S) as well as RBM20 knockout (KO) iPSCs. iPSC-derived engineered heart tissues made from these cell lines recapitulated contractile dysfunction of RBM20-associated DCM and revealed greater dysfunction with missense mutations than KO. Analysis of RBM20 RNA binding by eCLIP revealed a gain-of-function preference of mutant RBM20 for 3' UTR sequences that are shared with amyotrophic lateral sclerosis (ALS) and processing-body associated RNA binding proteins (FUS, DDX6). Deep RNA sequencing revealed that the RBM20 R636S mutant has unique gene, splicing, polyadenylation and circular RNA defects that differ from RBM20 KO, impacting distinct cardiac signaling pathways. Splicing defects specific to KO or R636S mutations were supported by data from R636S gene-edited pig hearts and eCLIP. Super-resolution microscopy verified that mutant RBM20 maintains limited nuclear localization potential; rather, the mutant protein associates with cytoplasmic processing bodies (DDX6) under basal conditions, and with stress granules (G3BP1) following acute stress. Taken together, our results highlight a novel pathogenic mechanism in cardiac disease through splicing-dependent and -independent pathways that are likely to mediate differential contractile phenotypes and stress-associated heart pathology.

cell biology↗