Gliomas are primary malignant brain tumors. These tumors seem to be more and more frequent, not only because of a true increase in their incidence, but also due to the increase in life expectancy of the general population. Among gliomas, malignant gliomas and more specifically glioblastomas (GBM) are a challenge in their diagnosis and treatment. There are few effective therapies for these tumors, and patients with GBM fare poorly, even after aggressive surgery, chemotherapy, and radiation. Over the last decade, it is now appreciated that these tumors are composed of numerous distinct tumoral and non-tumoral cell populations, which could each influence the overall tumor biology and response to therapies. Monocytes have been proved to actively participate in tumor growth, giving rise to the support of tumor-associated macrophages (TAMs). In GBM, TAMs represent up to one half of the tumor mass cells, including both infiltrating macrophages and resident brain microglia. Infiltrating macrophages/monocytes constituted ~ 85% of the total TAM population, they have immune functions, and they can release a wide array of growth factors and cytokines in response to those factors produced by tumor and non-tumor cells from the tumor microenvironment (TME). A brief review of the literature shows that this cell population has been increasingly studied in GBM TME to understand its role in tumor progression and therapeutic resistance. Through the knowledge of its biology and protumoral function, the development of therapeutic strategies that employ their recruitment as well as the modulation of their immunological phenotype, and even the eradication of the cell population, can be harnessed for therapeutic benefit. This revision aims to summarize GBM TME and localization in tumor niches with special focus on TAM population, its origin and functions in tumor progression and resistance to conventional and experimental GBM treatments. Moreover, recent advances on the development of TAM cell targeting and new cellular therapeutic strategies based on monocyte/macrophages recruitment to eradicate GBM are discussed as complementary therapeutics.

Glioblastoma (GBM) is an aggressive brain cancer characterized by significant molecular and cellular heterogeneity, which complicates treatment efforts. Current standard therapies, including surgical resection, radiation, and temozolomide (TMZ) chemotherapy, often fail to achieve long-term remission due to tumor recurrence and resistance. A pro-oxidant environment is involved in glioma progression, with oxidative stress contributing to the genetic instability that leads to gliomagenesis. Evaluating pro-oxidant therapies in brain tumors is crucial due to their potential to selectively target and eradicate cancer cells by exploiting the elevated oxidative stress levels inherent in these malignant cells, thereby offering a novel and effective strategy for overcoming resistance to conventional therapies. This study investigates the therapeutic potential of doxorubicin (DOX) and photodynamic therapy (PDT) with Me-ALA, focusing on their effects on redox homeostasis. Basal ROS levels and antioxidant gene expression (NFE2L2, CAT, GSR) were quantitatively assessed across GBM cell lines, revealing significant variability probably linked to genetic differences. DOX and PDT treatments, both individually and in combination, were analyzed for their efficacy in inducing oxidative stress and cytotoxicity. An in silico analysis further explored the relationship between gene mutations and oxidative stress in GBM patients, providing insights into the molecular mechanisms underlying treatment responses. Our findings suggest that pro-oxidant therapies, such as DOX and PDT in combination, could selectively target GBM cells, highlighting a promising avenue for improving therapeutic outcomes in GBM.

Glioblastoma (GBM), the most aggressive and lethal primary brain tumor, poses a significant therapeutic challenge due to its highly invasive nature and resistance to conventional therapies, including surgery, chemotherapy, and radiotherapy. Despite advances in standard treatments, patient survival remains limited, requiring the exploration of innovative strategies. Photodynamic therapy (PDT) has emerged as a promising approach, leveraging light-sensitive photosensitizers (PSs), molecular oxygen, and specific light wavelengths to generate reactive oxygen species (ROS) that selectively induce tumor cell death. Originally developed for skin cancer, PDT has evolved to target more complex malignancies, including GBM. The refinement of second- and third-generation PS, coupled with advancements in nanotechnology, has significantly improved PDT’s selectivity, bioavailability, and therapeutic efficacy. Moreover, the combination of PDT with chemotherapy, targeted therapy, and immunotherapy, among other therapeutic modalities, has shown potential in enhancing therapeutic outcomes. This review provides a comprehensive analysis of the preclinical and clinical applications of PDT in GBM, detailing its mechanisms of action, the evolution of PS, and novel combinatory strategies that optimize treatment efficacy. However, several challenges remain, including overcoming GBM-associated hypoxia, enhancing PS delivery across the blood-brain barrier, and mitigating tumor resistance mechanisms. The integration of PDT with molecular and genetic insight, alongside cutting-edge nanotechnology-based delivery systems, may revolutionize GBM treatment, offering new prospects for improved patient survival and quality of life.

Background/Objectives: Glioblastoma (GBM) remains the most aggressive primary brain tumor in adults, with limited therapeutic options and poor prognosis despite maximal surgery, radiotherapy, and chemotherapy. The complex and immunosuppressive tumor microenvironment, pronounced intratumoral heterogeneity, and the presence of the blood–brain barrier (BBB) severely restrict the efficacy of conventional and emerging therapies. In this context, cell-based strategies leveraging macrophages, mesenchymal stromal cells (MSCs), and their derivatives have gained attention as “cellular allies” capable of modulating the GBM microenvironment and acting as targeted delivery platforms. Methods: This review systematically analyzes preclinical and early clinical literature on macrophage- and MSC-based therapeutic strategies in GBM, including engineered cells, extracellular vesicles (EVs), membrane-coated nanoparticles, and hybrid biomimetic systems. Studies were selected based on relevance to GBM biology, delivery across or bypass of the BBB, microenvironmental modulation, and translational potential. Evidence from in vitro models, orthotopic and syngeneic in vivo models, and available clinical trials was critically evaluated, with emphasis on efficacy endpoints, biodistribution, safety, and manufacturing considerations. Results: The reviewed evidence demonstrates that macrophages and MSCs can function as active therapeutic agents or delivery vehicles, enabling localized oncolysis, immune reprogramming, stromal and vascular remodeling, and enhanced delivery of viral, genetic, and nanotherapeutic payloads. EVs and membrane-based biomimetic platforms further extend these capabilities while reducing cellular risks. However, therapeutic efficacy is highly context-dependent, influenced by tumor heterogeneity, BBB integrity, delivery route, and microenvironmental dynamics. Clinical translation remains limited, with most approaches at preclinical or early-phase clinical stages. Conclusions: Cell-based and cell-derived platforms represent a promising but still evolving therapeutic paradigm for GBM. Their successful translation will require rigorous biomarker-driven patient selection, improved models that capture invasive GBM biology, scalable GMP-compliant manufacturing, and rational combination strategies to overcome adaptive resistance mechanisms.

Glioblastoma (GBM) is an aggressive brain cancer characterized by significant molecular and cellular heterogeneity, complicating treatment efforts. Current standard therapies, including surgical resection, radiation, and temozolomide (TMZ) chemotherapy, often fail to achieve long-term remission due to tumor recurrence and resistance. A pro-oxidant environment is in-volved in glioma progression, with oxidative stress contributing to the genetic instability that leads to gliomagenesis. However, the generation of reactive oxygen species (ROS) results in the dysregulation of antioxidant defenses in GBM cells, creating a vulnerability that can be thera-peutically exploited. Evaluating pro-oxidant therapies in brain tumors is crucial due to their po-tential to selectively target and eradicate cancer cells by exploiting the elevated oxidative stress levels inherent in these malignant cells, thereby offering a novel and effective strategy for overcoming resistance to conventional therapies. This study investigates the therapeutic potential of doxorubicin (DOX) and photodynamic therapy (PDT) with Me-ALA, focusing on their effects on redox homeostasis. Basal ROS levels and antioxidant gene expression (NFE2L2, CAT, GSR) were quantitatively assessed across GBM cell lines, revealing significant variability probably linked to genetic differences. DOX and PDT treatments, both individually and in combination, were ana-lyzed for their efficacy in inducing oxidative stress and cytotoxicity. An in silico analysis further explored the relationship between gene mutations and oxidative stress in GBM patients, providing insights into the molecular mechanisms underlying treatment responses. Our findings suggest that pro-oxidant therapies, such as DOX and PDT in combination, could selectively target GBM cells, highlighting a promising avenue for improving therapeutic outcomes in GBM.

Glioblastoma (GBM) remains one of the most lethal primary brain tumors due to its highly infiltrative nature, pronounced intratumoral heterogeneity, and the restrictive blood–brain barrier (BBB), which severely limit the efficacy of conventional therapies. Photodynamic therapy (PDT) offers a spatially and temporally controllable treatment modality; however, its clinical translation for GBM is hindered by insufficient tumor selectivity and suboptimal photosensitizer delivery to intracranial lesions. The purpose of this study was to develop and preclinically evaluate transferrin-functionalized conjugated polymer nanoparticles (CPNs) as a receptor-targeted nanoplatform to enhance BBB traversal, tumor cell uptake, and photodynamic therapeutic efficacy in GBM. F8BT-based CPNs doped with platinum(II) octaethylporphyrin (PtOEP) and stabilized with poly(styrene-co-maleic anhydride) (PSMA) were synthesized by controlled nanoprecipitation and covalently conjugated to holo-transferrin (holo-Tf) using EDC/NHS chemistry. Nanoparticles were characterized by dynamic light scattering, zeta potential, UV–visible and fluorescence spectroscopy, transmission electron microscopy, electrophoretic mobility, and protein quantification assays. Cellular uptake, receptor specificity, and photodynamic cytotoxicity were evaluated in GBM cell lines. Therapeutic efficacy was further assessed in an orthotopic U87MG-tdiRFP glioblastoma mouse model. Holo-Tf functionalization increased nanoparticle hydrodynamic diameter, reduced surface charge magnitude, and introduced a protein-specific absorbance feature, while preserving colloidal stability and optical properties. Protein quantification assays confirmed retention of more than 70% of the input holo-Tf. In vitro, holo-Tf CPNs showed significantly enhanced uptake in TfR-high U87MG cells compared with non-functionalized CPNs (42% vs 18% nanoparticle-positive cells at 1 h; gMFI 211 vs 73 at 4 h), which was reduced by excess free holo-Tf, indicating receptor-mediated uptake. PDT mediated by holo-Tf CPNs produced greater phototoxicity in vitro and, in vivo, reduced tumor fluorescence and prolonged survival relative to controls. Transferrin functionalization enhances receptor-directed delivery and PDT efficacy of conjugated polymer nanoparticles in GBM, supporting their further optimization and translational development.