Poly(lactic-glycolic acid) (PLGA) is a biocompatible bio-scaffold material, but its own hydrophobic and electrically neutral surface limits its application as a cell scaffold. Polymer materials, mimics ECM materials, and organic material have often been used as coating materials for PLGA cell scaffolds to improve the poor cell adhesion of PLGA and enhance tissue adaptation. These coating materials can be modified on the PLGA surface via simple physical or chemical methods, and coating multiple materials can simultaneously confer different functions to the PLGA scaffold; not only does this ensure stronger cell adhesion but it also modulates cell behavior and function. This approach to coating could facilitate the production of more PLGA-based cell scaffolds. This review focuses on the PLGA surface-modified materials, methods, and applications, and will provide guidance for PLGA surface modification.

Background: The immunotherapeutic approach utilizing Natural Killer (NK) cells for cancer treatment has garnered significant interest owing to its inherent cytotoxicity, immunomodulatory properties, demonstrated safety in in vivo studies. However, multiple immunosuppressive mechanisms in the tumor microenvironment (TME) suppress the anticancer effect of NK cells in the treatment of solid tumors. Herein, a smart NK cell drug delivery system (DDS) with photo-responsive and TME-responsive properties was designed. Methods: The NK cell DDS consists of two parts: the carrier is living NK cell with pH-low (abbreviated as NK_pH) insertion peptide on its surface, the cargo is reductive-responsive nanogel (NG) encapsulated siRNA and photosensitizer (abbreviated as SP-NG), the final carrier was abbreviated as SP-NG@ NK_pH. Firstly, pHLip helped artificially modified NK cell target and anchor onto cancer and exert the efficacy of cellular immunotherapy. Then, the strategy of combining photoactivation and bioreduction responsiveness achieved the precise release of cargos in cancer cells. Finally, the DDS combined the effect of the immunotherapy of NK cell, the gene therapy of siRNA, and the photodynamic therapy of photosensitizer. Results: Under near-infrared laser irradiation, SP-NG@NK_pH induced an increase in reactive oxygen species (ROS) within cells, exacerbated cell membrane permeability, and allowed for rapid drug release. Within the tumor microenvironment (TME), NG exhibits highly sensitive reducibility for drug release. The SP-NG released from NK cells can be uptaken by tumor cells. When exposed to near-infrared laser irradiation, SP-NG@NK_pH demonstrates significant tumor-targeting specificity and cytotoxicity. Discussion: The combined effect of the immunotherapy of NK cell, the gene therapy of siRNA, and the photodynamic therapy of photosensitizer obtained a stronger cancer killing effect in vitro and in vivo. Therefore, this versatile NK cell DDS exhibits a good clinical application prospect.

Objectives: This study developed pH/enzyme-sensitive polymeric HA-AAN-DOX (HAD) micelles to resolve the limited targeting specificity of chemotherapy drugs. Methods: Hyaluronic acid (HA) and the chemotherapeutic agent doxorubicin (DOX) were conjugated via a hydrazone linkage utilizing an Ala-Ala-ASP tripeptide (AAN) as the connecting moiety, which is sensitive to the legumain enzyme. DOX was delivered via HAD micelles, which were activated by both hyaluronidase and the legumain enzyme. Key findings: The results revealed the remarkable antitumor efficacy of these micelles both in vivo and in vitro. Compared with that of doxorubicin hydrochloride (DOX·HCl), the incidence of toxic side effects was significantly reduced with the HAD micelle treatment. As a result, micelles composed of hyaluronic acid and doxorubicin (HAD) offer a reliable and effective method for drug delivery, with the potential to optimize the therapeutic impact of chemotherapeutic agents on tumors by reducing unintended side effects. Conclusions: Micelles composed of hyaluronic acid and doxorubicin (HAD) offer a reliable and effective method for drug delivery, with the potential to optimize the therapeutic impact of chemotherapeutic agents on tumors by reducing unintended side effects.

Thorough understanding and accurate prediction of in vivo drug release are essential for developing long‐acting microsphere systems. However, the fate of microspheres after prolonged tissue residence and the regulatory role of physiological factors remain unclear, hindering elucidation of release mechanisms. Herein, the dynamic evolution of microsphere depots and associated microenvironmental changes were studied. Beyond poly(lactic‐co‐glycolic acid) (PLGA) and API effects, microsphere depot behavior is partly regulated by conserved biological processes, with skeletal muscle and subcutaneous tissue employing distinct adaptive strategies to restore homeostasis. Using these insights, we developed the in vivo release predictive models (IVRPMs) that establish a true IVIVC for naltrexone PLGA microspheres. The IVRPMs demonstrated broad applicability across microspheres with different APIs and PLGA types, and showed promising translational potential in beagle and human studies. This study shifts the research paradigm from “material‐dominated release” to “organism‐material coevolution”, addressing a key question in depot formulation fate.