Osteosarcomas (OS), which arise from primitive mesenchymal cells, are the most prevalent malignant bone tumors, particularly affecting adolescents (Ritter & Osteosarcoma, 2010). The typical treatment protocol for OS encompasses radical surgical removal, followed by both pre- and post-operative chemotherapy(Chen et al., 2021). Despite these measures, the tumor's aggressive nature and propensity for early spread, notably to the lungs(Yu et al., 2023), presents a challenge for existing anti-cancer drugs, as they struggle to manage the high rates of metastasis and relapse associated with OS (Chen et al., 2021). In addition, current chemotherapeutic agents all have multiple drawbacks such as low water solubility, fast clearance, and poor targeting and high toxicity, which amplify their difficulties in responding to tumor treatment(Gangi et al., 2014). Addressing drug targeting and attenuating its clearance has become a pain point for treating OS and improving its prognosis (Jang et al., 2013).

The tumor microenvironment (TME) is a complex system that includes vascular endothelial cells, cancer-associated fibroblasts, immune cells, cancer stem cells (CSCs), pericytes, and other cell types(Huai et al., 2019). senescence-associated secretory phenotypes (SASPs), which are released during cellular senescence, cause the TME to be remodeled by releasing a variety of cytokines, chemokines, and growth factors, and tumor-associated macrophages, the major infiltrating immune cells in the TME, are similarly affected by the influence of SASPs(Du et al., 2024). It has been shown that macrophages have two different states of activated polarization, with M2 macrophages being the predominant cells in the TME that promote tumor progression in the TME and exhibit an immunosuppressive state, whereas M1 macrophages exhibit the exact opposite of this(Chen et al., 2021). Therefore, targeting M2 macrophages to increase their depletion, or converting them to M1 macrophages, or changing the composition of M1/M2 macrophages has become one of the strategies for antitumor therapy in TME(Tiwari et al., 2022).

MicroRNAs, small endogenous RNAs of about 19–25 nucleotides, are key regulators of gene expression, primarily involved in post-transcriptional regulation. MicroRNA mimics and microRNA inhibitors have the potential to become novel therapeutic agents(Lu & Rothenberg, 2018). The current study concluded that the expression of microRNAs is associated with cancer, mainly in that microRNAs can act as oncogenes and tumor suppressor genes(Garzon et al., 2006). Furthermore, microRNAs are also important in TME. For instance, microRNAs can directly control tumor metastasis and also regulate metastasis as a communication bridge between tumor cells and TME cells(Solé & Lawrie, 2021). In addition, microRNAs can also be used as a non-invasive diagnostic/prognostic marker, as well as an effective target for tumor therapy, e.g., microRNA-495, widely found in diverse cancers, serves as a crucial diagnostic and therapeutic marker(Maharati et al., 2023). MiR-665, the focus of this study, has been demonstrated to exert a role in a range of diseases. For instance, it has been shown to inhibit pyroptosis, thereby attenuating myocardial ischemia/reperfusion injury(Wang et al., 2023), and to play a role in microglia following spinal cord injury(Liu et al., 2021). Furthermore, its involvement in the development of various cancers. For example, it was noted that miR-665 in large B cell lymphoma (DLBCL) patients with decreased expression in serum exosomes, and overexpression of miR-665 can inhibit DLBCL progression by targeting LIM and SH3 protein 1 (LASP1) and MYC(Wang et al., 2022). Similarly, miR-665 can be used as an effective diagnostic biomarker in hepatocellular carcinoma screening in Egyptian chronic hepatitis C virus-infected patients(Mohamed et al., 2020). Furthermore, circ_0009092 gene has been shown to function as a sponge to adsorb miR-665. This, in turn, has been demonstrated to enhance NLK expression and increase further binding to ST3, thereby inhibiting gene CCL2 expression to achieve inhibition of tumour-associated macrophages (TAMs) recruitment in TME, and ultimately inhibit colorectal cancer (CRC) progression.(Song et al., 2023).

Poly lactic-co-glycolic acid (PLGA), one of the earliest developed synthetic polymers, is inherently biodegradable and biocompatible, controlled release of drugs, protection of drugs or genes from catabolism, and targeted modification of surfaces, among many other properties(Hashemi et al., 2020). The nanoparticles constructed on the basis of PLGA are widely used in many fields of medical research due to the above-mentioned properties of PLGA, the most important of which is as a drug delivery system(Yamamoto et al., 2012). Upon entering the human body, PLGA nanoparticles undergo a metabolic process that results in the production of lactic acid and hydroxyacetic acid, thereby becoming part of the body's normal metabolic processes, while the substances they carry are released(Rocha et al., 2022). Moreover, PLGA nanoparticles can carry not only chemotherapeutic drugs(Caban-Toktas et al., 2020, Devulapally et al., 2016), but also peptides(Ren et al., 2021), traditional Chinese medicine(Zhou et al., 2021), MicroRNAs(Shams et al., 2022), and even biodegradable PLGA nanoparticles for photothermal therapy (PTT) (Valcourt et al., 2019). Recently, cell membrane biomimetic nanoparticles have become a new hotspot(Sun et al., 2023, Yang et al., 2018). Nanoparticles, after being modified by cell membranes, can achieve long-term circulation without being cleared and can target the delivery of contents to specific sites. The tumor cell membrane retains surface antigens and proteins from the original tumor cells. These components can specifically recognize and bind to the same type of tumor cells. This “homologous targeting” mechanism enables tumor cell membrane − mimetic nanoparticles to effectively recognize and target tumor tissues (Cancer cell, 2025, Li et al., 2024). Likewise, the tumor cell membrane is capable of mimicking the immune − evasion characteristics of tumor cells, thereby avoiding clearance by the immune system. This enables tumor cell membrane − mimetic nanoparticles to circulate in the body for a longer period, increasing their accumulation at the tumor site(Zhang et al., 2023). Additionally, tumor blood vessel endothelial cells express specific markers (such as αvβ3 integrin), and tumor cell membrane − mimetic nanoparticles can target tumor blood vessels through these markers, and then permeate into the interior of the tumor tissue(Graf et al., 2012, Zhao and Yan, 2022). Moreover, hybrid membranes (HM) offer advantages over monotypic membrane, including enhanced active targeting, improved immune evasion, and greater biocompatibility. It is due to these aforementioned properties that the application of HM can enhance the therapeutic effect(Liao et al., 2020, Pan et al., 2022);

In this study, we successfully constructed an HM@PLGA/miR-665 delivery system using the PLGA nanoparticles and hybrid membranes derived from osteosarcoma cells and macrophages. This system could encapsulate miR-665 and provide a stable delivery of miR-665 to the OS tumors’ areas. Hybrid membranes provided targeted functionality. When nanoparticles reached the tumor site, they released miR-665. Then miR-665 inhibited OS progression by targeting macrophages and altering the ratio of M1/M2 macrophages in TME. Fig. 1 presents our research details.