# Interleukin‐12 sustained release system promotes hematopoietic recovery after radiation injury

## TL;DR

A new injectable hydrogel slowly releases interleukin-12 to help repair blood cell production after radiation injury.

## Contribution

A novel hydrogel system for sustained IL-12 delivery that promotes hematopoietic recovery after radiation.

## Key findings

- Local administration of RGD-Alg/Laponite@IL-12 increased survival and hematopoietic recovery in irradiated mice.
- The hydrogel activated the IL-12R-PI3K/AKT signaling axis, enhancing mesenchymal stem cell function and microenvironment repair.
- This strategy offers a new therapeutic approach for radiation-induced hematopoietic injury.

## Abstract

The continuous production of mature blood cell lineages is maintained by hematopoietic stem cells but they are highly susceptible to damage by ionizing radiation (IR) that induces death. Thus, devising therapeutic strategies that can mitigate hematopoietic toxicity caused by IR would benefit acute radiation syndrome (ARS) victims and patients receiving radiotherapy. Herein, we describe the preparation of an injectable hydrogel formulation based on Arg‐Gly‐Asp‐alginate (RGD‐Alg) and Laponite using a simple mixing method that ensured a slow and sustained release of interleukin‐12 (IL‐12) (RGD‐Alg/Laponite@IL‐12). The local administration of RGD‐Alg/Laponite@IL‐12 increased survival rates and promoted the hematopoietic recovery of mice who had received sublethal‐dose irradiation. Local intra‐bone marrow (intra‐BM) injection of RGD‐Alg/Laponite@IL‐12 hydrogel effectively stimulated IL12 receptor‐phosphoinositide 3‐kinase/protein kinase B (IL‐12R‐PI3K/AKT) signaling axis, which promoted proliferation and hematopoietic growth factors secretion of BM mesenchymal stem/stromal cells. This signaling axis facilitates the repair of the hematopoietic microenvironment and plays a pivotal role in hematopoietic reconstitution. In conclusion, we describe a biomaterial‐sustained release of IL‐12 for the treatment of irradiated hematopoietic injury and provide a new therapeutic strategy for hematopoietic ARS.

Schematic illustration of the mechanism of Arg‐Gly‐Asp‐alginate (RGD‐Alg)/Laponite@IL‐12 hydrogel as an effective therapeutic strategy to treat radiation‐induced hematopoietic injury.