An injectable acellular matrix scaffold with absorbable permeable nanoparticles improves the therapeutic effects of docetaxel on glioblastoma

Decellularized extracellular matrix as a drug delivery carrier

Tissue engineering and regenerative medicine approaches seek to enhance biomaterial mimicry with the goal of driving cell recruitment, proliferation, and differentiation. Decellularized extracellular matrix (dECM) biomaterials have emerged as a promising platform for biomaterials development as they capture the complexity of native tissues and offer a rich environment of signals to guide cellular responses. However, the decellularization process can affect both the structure and composition of the ECM. Recent efforts have focused on leveraging dECM as drug delivery carriers for controlled release of bioactive molecules. This review highlights current strategies for incorporating therapeutic agents into dECM which include encapsulation within hydrogel formulations, direct bulk absorption of biomolecules, and affinity-based binding and conjugation. Each method offers unique advantages for modulating release profiles, which can range from rapid initial burst to prolonged, sustained release, depending on factors such as crosslinking density, degradation rate, and specific interactions of biomolecules with dECM components such as glycosaminoglycans.

Decellularization of various tissues and organs through chemical methods

Due to the increase in demand for donor organs and tissues during the past 20 years, new approaches have been created. These methods include, for example, tissue engineering in vitro and the production of regenerative biomaterials for transplantation. Applying the natural extracellular matrix (ECM) as a bioactive biomaterial for clinical applications is a unique approach known as decellularization technology. Decellularization is the process of eliminating cells from an extracellular matrix while preserving its natural components including its structural and functional proteins and glycosaminoglycan. This can be achieved by physical, chemical, or biological processes. A naturally formed three-dimensional structure with a biocompatible and regenerative structure is the result of the decellularization process. Decreasing the biological factors and antigens at the transplant site reduces the risk of adverse effects including inflammatory responses and immunological rejection. Regenerative medicine and tissue engineering applications can benefit from the use of decellularization, a promising approach that provides a biomaterial that preserves its extracellular matrix.

Ultra-small micelles together with UTMD enhanced the therapeutic effect of docetaxel on Glioblastoma

Owing to the difficult-to-penetrate blood-brain barrier (BBB), glioblastoma (GBM) doesn't respond well to the current chemical therapeutics. In this study, ultra-small micelles (NMs) self-assembled by RRR-a-tocopheryl succinate-grafted-ε-polylysine conjugate (VES-g-ε-PLL) as the delivery vehicle of chemical therapeutics in conjunction with ultrasound-targeted microbubble destruction (UTMD) to surmount BBB and treat GBM. Docetaxel (DTX) as a hydrophobic model drug was incorporated into NMs. DTX-loaded micelles (DTX-NMs) with 3.08% of drug loading exhibited a hydrodynamic diameter (33.2 nm) and positive Zeta potential (16.9 mV), having a remarkable tumor-permeating capacity. Furthermore, DTX-NMs presented good stability in physiologic condition. The sustained- release profile of DTX-NMs was also displayed by dynamic dialysis. Treatment of DTX-NMs together with UTMD led to more pronounced apoptosis of C6 tumor cells than DTX-NMs alone. Moreover, compared with the DTX solution or DTX-NMs alone, the combination of DTX-NMs with UTMD had a stronger inhibitory effect on tumor growth for GBM-bearing rats. The median survival period of GBM-bearing rats was extended to 75 days in the DTX-NMs+UTMD group from under 25 days in the control group. The invasive growth of glioblastoma was largely inhibited by the combination of DTX-NMs with UTMD, which was demonstrated by staining of Ki67, caspase-3, and CD31, together with TUNEL assay. In conclusion, the combination of ultra-small micelles (NMs) with UTMD may be a promising strategy to overcome the limitations of the first-line chemotherapeutics against GBM.

Scaffold-based spheroid models of glioblastoma multiforme and its use in drug screening

Among several types of brain cancers, glioblastoma multiforme (GBM) is a terminal and aggressive disease with a median survival of 15 months despite the most intensive surgery and chemotherapy. Preclinical models that accurately reproduce the tumor microenvironment are vital for developing new therapeutic alternatives. Understanding the complicated interactions between cells and their surroundings is essential to comprehend the tumor's microenvironment, however the monolayer cell culture approach falls short. Numerous approaches are used to develop GBM cells into tumor spheroids, while scaffold-based spheroids provides the opportunity to investigate the synergies between cells as well as cells and the matrix. This review summarizes the development of various scaffold-based GBM spheroid models and the prospective for their use as drug testing systems.

Injectable local drug delivery systems for glioblastoma: a systematic review and meta-analysis of progress to date

Glioblastoma (GBM) is an aggressive malignant cancer associated with bleak prognosis and high mortality. The current standard of care for GBM is maximum surgical resection plus radiotherapy and temozolomide (TMZ) chemotherapy. The blood brain barrier (BBB) remains the main obstacle for chemotherapy and severely limits the choice of therapeutic agents. Local treatment allows drugs to circumvent the BBB and reduces systemic side effects. Despite much research effort, to date, no drug delivery system (DDS) designed to be directly injected into brain tumors has been clinically approved, and a systematic overview of the progress in this field, or lack thereof, is missing. In this review, a systematic search of pre-clinical literature was conducted which resulted in 36 original articles on injectable DDS for local treatment of GBM which met the inclusion criteria. A wide range of injectable DDS have been developed and tested pre-clinically which include nanoparticles, liposomes, microspheres, hydrogels and others. meta-Analyses of the included studies showed that, overall, local administration of injectable DDS was beneficial to increase the animal's survival time. Finally, this review summarized the therapeutic effect after local treatment and discussed the shortcomings of the experimental setting in in vivo studies.

Extracellular matrix extraction techniques and applications in biomedical engineering

The concept of tissue engineering involves regeneration and repair of damaged tissue and organs using various combinations of cells, growth factors and scaffolds. The extracellular matrix (ECM) forms the integral part of the scaffold to induce cell proliferation thereby leading to new tissue formation. Decellularization technique provides decellularized ECM (dECM), free of cells while preserving the in vivo biomolecules. In this review, we focus on the detailed methodology of diverse decellularization techniques for various organs of different animals, and the biomedical applications employing the dECM. A culmination of different methods of decellularization is optimized, which offers a suitable microenvironment mimicking the native in vivo topography for in vitro organ regeneration. A detailed assessment of the dECM provides information on the microarchitecture, presence of ECM proteins, biocompatibility and cell proliferation. dECM has also been processed as scaffolds and drug-delivery vehicles, and utilized for regeneration.

Local delivery to malignant brain tumors: potential biomaterial-based therapeutic/adjuvant strategies

Glioblastoma (GBM) is the most aggressive malignant brain tumor and is associated with a very poor prognosis. The standard treatment for newly diagnosed patients involves total tumor surgical resection (if possible), plus irradiation and adjuvant chemotherapy. Despite treatment, the prognosis is still poor, and the tumor often recurs within two centimeters of the original tumor. A promising approach to improving the efficacy of GBM therapeutics is to utilize biomaterials to deliver them locally at the tumor site. Local delivery to GBM offers several advantages over systemic administration, such as bypassing the blood-brain barrier and increasing the bioavailability of the therapeutic at the tumor site without causing systemic toxicity. Local delivery may also combat tumor recurrence by maintaining sufficient drug concentrations at and surrounding the original tumor area. Herein, we critically appraised the literature on local delivery systems based within the following categories: polymer-based implantable devices, polymeric injectable systems, and hydrogel drug delivery systems. We also discussed the negative effect of hypoxia on treatment strategies and how one might utilize local implantation of oxygen-generating biomaterials as an adjuvant to enhance current therapeutic strategies.

Improved Anti-Triple Negative Breast Cancer Effects of Docetaxel by RGD-Modified Lipid-Core Micelles

Purpose

A novel RGD-modified PEGylated lipid-core micelle delivery system was designed to improve the anti-cancer effect of docetaxel on triple negative breast cancer (TNBC).

Methods

The tumor-targeted lipid-core micelles loaded with docetaxel were prepared and characterized. Their morphology, particle size, zeta potential, entrapment efficiency, release profiles, and targeting effects were studied. The antitumor effects of the docetaxel-loaded nano-micelles were investigated in a MDA-MB-231 cell model in vitro and a MDA-MB-231 xenograft model in vivo.

Results

The prepared RGD-modified docetaxel-loaded lipid-core micelles were spherical with a particle size of 16.44±1.35 nm, zeta potential of −19.24±1.24 mV, and an encapsulation efficiency of 96.52±0.43%. The drug delivery system showed sustained release properties and could significantly enhance docetaxel uptake by MDA-MB-231 tumor cells in vitro, which was proved to be a caveolae pathway mediated process requiring ATP, Golgi apparatus, and acid lysosomes. The results of the pharmacokinetic study displayed that the area under the curve of the targeted micelles was 3.2-times higher than that of docetaxel commercial injections. Furthermore, in a MDA-MB-231 tumor-bearing mice model, a higher antitumor efficacy than docetaxel commercial injections was displayed, and the safety experiments showed that the micellar material did not cause major organ damage after intravenous administration in mice.

Conclusion

The novel RGD-modified PEGylated lipid-core micelle delivery system significantly improved the antitumor effects and reduced the side-effects of docetaxel, providing a promising therapeutics for the treatment of TNBC.

Docetaxel-loaded folate-modified TPGS-transfersomes for glioblastoma multiforme treatment

Glioblastoma multiforme (GBM) is a first primary Central Nervous System tumor with high incidence and lethality. Its treatment is hampered by the difficulty to overcome the blood-brain barrier (BBB) and by the non-specificity of chemotherapeutics to tumor cells. This study was based on the development characterization and in vitro efficacy of folate-modified TPGS transfersomes containing docetaxel (TF-DTX-FA) to improve GBM treatment. TF-DTX-FA and unmodified transfersomes (TF-DTX) were prepared through thin-film hydration followed by extrusion technique and characterized by physicochemical and in vitro studies. All formulations showed low particles sizes (below 200 nm), polydispersity index below 0.2, negative zeta potential (between -16.75 to -12.45 mV) and high encapsulation efficiency (78.72 ± 1.29% and 75.62 ± 0.05% for TF-DTX and TF-DTX-FA, respectively). Furthermore, cytotoxicity assay of TF-DTX-FA showed the high capacity of the nanocarriers to reduce the viability of U-87 MG in both 2D and 3D culture models, when compared with DTX commercial formulation and TF-DTX. In vitro cellular uptake assay indicated the selectivity of transfersomes to tumoral cells when compared to normal cells, and the higher ability of TF-DTX-FA to be internalized into 2D U-87 MG in comparison with TF-DTX (72.10 and 62.90%, respectively, after 24 h). Moreover, TF-DTX-FA showed higher permeability into 3D U-87 MG spheroid than TF-DTX, suggesting the potential FA modulation to target treatment of GBM.

Delivery of pOXR1 through an injectable liposomal nanoparticle enhances spinal cord injury regeneration by alleviating oxidative stress

Oxidation resistance 1 (OXR1) is regarded as a critical regulator of cellular homeostasis in response to oxidative stress. However, the role of OXR1 in the neuronal response to spinal cord injury (SCI) remains undefined. On the other hand, gene therapy for SCI has shown limited success to date due in part to the poor utility of conventional gene vectors. In this study, we evaluated the function of OXR1 in SCI and developed an available carrier for delivering the OXR1 plasmid (pOXR1). We found that OXR1 expression is remarkably increased after SCI and that this regulation is protective after SCI. Meanwhile, we assembled cationic nanoparticles with vitamin E succinate-grafted ε-polylysine (VES-g-PLL) (Nps). The pOXR1 was precompressed with Nps and then encapsulated into cationic liposomes. The particle size of pOXR1 was compressed to 58 nm, which suggests that pOXR1 can be encapsulated inside liposomes with high encapsulation efficiency and stability to enhance the transfection efficiency. The agarose gel results indicated that Nps-pOXR1-Lip eliminated the degradation of DNA by DNase I and maintained its activity, and the cytotoxicity results indicated that pOXR1 was successfully transported into cells and exhibited lower cytotoxicity. Finally, Nps-pOXR1-Lip promoted functional recovery by alleviating neuronal apoptosis, attenuating oxidative stress and inhibiting inflammation. Therefore, our study provides considerable evidence that OXR1 is a beneficial factor in resistance to SCI and that Nps-Lip-pOXR1 exerts therapeutic effects in acute traumatic SCI.

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OXR1 is upregulated after SCI and may provide a protective effect in response to neural injury.

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OXR1 plasmid is condensed by VES-g-PLL micelles and then encapsulated into cationic liposomes.

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Liposome complexes significantly enhance the OXR1 protein expression in vivo and in vitro.

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Overexpressed OXR1 relieving oxidative stress after SCI through Nrf-2/HO-1 pathway.

Vitamin E succinate with multiple functions: A versatile agent in nanomedicine-based cancer therapy and its delivery strategies

Vitamin E succinate (VES), a succinic acid ester of vitamin E, is one of the most effective anticancer compounds of the vitamin E family. VES can inhibit tumor growth by multiple pathways mainly involve tumor proliferation inhibition, apoptosis induction, and metastasis prevention. More importantly, the mitochondrial targeting and damaging property of VES endows it with great potential in exhibiting synergetic effect with conventional chemotherapeutic drugs and overcoming multidrug resistance (MDR). Given the lipophilicity of VES that hinders its bioavailability and therapeutic activity, nanotechnology with multiple advantages has been widely explored to deliver VES and opened up new avenues for its in vivo application. This review aims to introduce the anticancer mechanisms of VES and summarize its delivery strategies using nano-drug delivery systems. Specifically, VES-based combination therapy for synergetic anticancer effect, MDR-reversal, and oral chemotherapy improvement are highlighted. Finally, the challenges and perspectives are discussed.

Tumor cellular membrane camouflaged liposomes as a non-invasive vehicle for genes: specific targeting toward homologous gliomas and traversing the blood-brain barrier

Gene therapy aimed at malignant gliomas has shown limited success to date due in part to the inability of conventional gene vectors to achieve widespread and specific gene transfer throughout the highly disseminated tumor zone within the brain. Herein, cationic micelles assembled from vitamin E succinate-grafted ε-polylysine (VES-g-PL) polymers were first exploited to condense TRAIL plasmids (pDNA). Thereafter, the condensed pDNA was further encapsulated into liposomes camouflaged with tumor cellular membrane. The condensed pDNA was successfully encapsulated into the inner aqueous compartments of the liposomes instead of the surface, which was proved based on the TEM morphology and decreased cytotoxicity toward HUVEC and PC-12 cells. Moreover, glioma cell membrane (CM) was easily inlaid into the lipid layer of the pDNA-loaded liposomes to form T@VP-MCL, as shown via TEM, AFM, and SDS-PAGE analysis. T@VP-MCL exhibited good particle size stability at strong ion strength and effectively protected pDNA from DNase I induced degradation. Owing to the CM-associated proteins, T@VP-MCL specifically targeted not only ICAM-1 overexpressed in glioma RBMECs but also homogenous glioma cells. Moreover, in vivo imaging showed that T@VP-MCL was effectively located in orthotopic gliomas of rats after intravenous administration, resulting in effective tumor growth inhibition, prolonging the lives of the rats. The mechanism of T@VP-MCL traversing the BBB was highly associated with the down-regulation of the tight junction-associated proteins ZO-1 and claudin-5. Conclusively, T@VP-MCL designed herein may be a potential carrier for therapeutic genes.

Antiangiogenic Targets for Glioblastoma Therapy from a Pre-Clinical Approach, Using Nanoformulations

Glioblastoma (GBM) is the most aggressive tumor type whose resistance to conventional treatment is mediated, in part, by the angiogenic process. New treatments involving the application of nanoformulations composed of encapsulated drugs coupled to peptide motifs that direct drugs to specific targets triggered in angiogenesis have been developed to reach and modulate different phases of this process. We performed a systematic review with the search criterion (Glioblastoma OR Glioma) AND (Therapy OR Therapeutic) AND (Nanoparticle) AND (Antiangiogenic OR Angiogenesis OR Anti-angiogenic) in Pubmed, Scopus, and Cochrane databases, in which 312 articles were identified; of these, only 27 articles were included after selection and analysis of eligibility according to the inclusion and exclusion criteria. The data of the articles were analyzed in five contexts: the characteristics of the tumor cells; the animal models used to induce GBM for antiangiogenic treatment; the composition of nanoformulations and their physical and chemical characteristics; the therapeutic anti-angiogenic process; and methods for assessing the effects on antiangiogenic markers caused by therapies. The articles included in the review were heterogeneous and varied in practically all aspects related to nanoformulations and models. However, there was slight variance in the antiangiogenic effect analysis. CD31 was extensively used as a marker, which does not provide a view of the effects on the most diverse aspects involved in angiogenesis. Therefore, the present review highlighted the need for standardization between the different approaches of antiangiogenic therapy for the GBM model that allows a more effective meta-analysis and that helps in future translational studies.

In vitro and in vivo evaluation of didymin cyclodextrin inclusion complexes: characterization and chemosensitization activity

Didymin is a dietary flavonoid that first found in citrus fruits, and possesses antioxidant properties. Our preliminary experiments first discovered that didymin was able to sensitize the resistant cancer cells against chemotherapeutics and combat multidrug resistance. However, its poor aqueous solubility and resultant low bioavailability limit its potentials as an adjuvant phytochemical drug for chemotherapy. Thus, this study prepared the inclusion complex of didymin with β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin to improve its bioavailability and then evaluate their chemosensitization effects. The didymin inclusion complexes formulation was prepared and their host-guest structure was characterized by FT-IR, PXRD, DSC, and SEM techniques. In vitro/in vivo results demonstrated that didymin inclusion complex enhanced its water solubility and orally bioavailability. Furthermore, didymin inclusion complex exerted considerable chemosensitivity potency, and improve the anti-tumor effects of chemotherapeutics in vivo. Therefore, didymin inclusion complex could provide a safe, effective, economical, and adjuvant drug for future treatment of chemoresistant cancers.

Exploiting crosslinked decellularized matrix to achieve uterus regeneration and construction

Decellularized extracellular matrix (dECM) has been considered as a promising scaffold in xenotransplantation, yet natural tissue dECM is often mechanically weak and rapidly degraded, compromising the outcomes. How to restore the mechanical strength and optimise the in vivo degradation, but maintain the microstructure and maximumly suppress the immune rejection, remains challenging. For this aim, we prepared and characterised various crosslinked decellularized rabbit uterus matrix (dUECM) and evaluated in vivo performance after uterus xenotransplantation from rabbit to rat. Naturally derived genipin (GP) and procyanidins (PC) were chosen to crosslink the dUECM, producing significant mechanical enhanced crosslinked-dUECM along with prolonged enzymatic degradation rate. Xenogeneic subcutaneous graft studies revealed that PC- and GP-crosslinked dUECM experienced significant cell infiltration and caused low immune reactions, indicating the desired biocompatibility. In vivo transplantation of GP- and PC-crosslinked dUECM to a uterus circular excised rat yielded excellent recellularization ability and promoted uterus regeneration after 90 days. While the reconstruction efficacy of crosslinked dUECM is highly depended on the crosslinking degree, crosslinking condition must be carefully evaluated to balance the role of crosslinked dECM in mechanical and biological support for tissue regeneration promotion.

3D-bioprinted functional and biomimetic hydrogel scaffolds incorporated with nanosilicates to promote bone healing in rat calvarial defect model

Three-dimensional (3D) bioprinting is an extremely convenient biofabrication technique for creating biomimetic tissue-engineered bone constructs and has promising applications in regenerative medicine. However, existing bioinks have shown low mechanical strength, poor osteoinductive ability, and lacking a suitable microenvironment for laden cells. Nanosilicate (nSi) has shown to be a promising biomaterial, due to its unique properties such as excellent biocompatibility, degrade into nontoxic products, and with osteoinductive properties, which has been used in bone bioprinting. However, the long term bone healing effects and associating risks, if any, of using nSi in tissue engineering bone scaffolds in vivo are unclear and require a more thorough assessment prior to practical use. Hence, a functional and biomimetic nanocomposite bioink composed of rat bone marrow mesenchymal stem cells (rBMSCs), nSi, gelatin and alginate for the 3D bioprinting of tissue-engineered bone constructs is firstly demonstrated, mimicking the structure of extracellular matrix, to create a conducive microenvironment for encapsulated cells. It is shown that the addition of nSi significantly increases the printability and mechanical strength of fabricated human-scale tissue or organ structures (up to 15 mm height) and induces osteogenic differentiation of the encapsulated rBMSCs in the absence of in vitro osteoinductive factors. A systematic in vivo research of the biomimetic nanocomposite bioink scaffolds is further demonstrated in a rat critical-size (8 mm) bone defect-repair model. The in vivo results demonstrate that the 3D bioprinted nanocomposite scaffolds can significantly promote the bone healing of the rat calvarial defects compared to other scaffolds without nSi or cells, and show rarely side effects on the recipients. Given the above advantageous properties, the 3D bioprinted nanocomposite scaffolds can greatly accelerate the bone healing in critical bone defects, thus providing a clinical potential candidate for orthopedic applications.

Aloe/poloxamer hydrogel as an injectable β-estradiol delivery scaffold with multi-therapeutic effects to promote endometrial regeneration for intrauterine adhesion treatment

Intrauterine adhesion (IUA) is characterized by endometrial stromal replaced with fibrous tissue during the trauma or operation induced injury. Current clinic IUA management mainly involves surgical removal of the connective tissues and physical separation and often results in reoccurrence. It is of clinic interest to directly address the issue via facilitating the endometrial repair and thereby inhibiting the formation of re-adhesion. To this end, we designed a nanocomposite aloe/poloxamer hydrogel for β-estradiol (E2) intrauterine delivery to exert multi-therapeutic effects and promote endometrial regeneration for IUA treatment. Nanoparticulate decellularized uterus (uECMNPs) was prepared to encapsulate E2 (E2@uECMNPs), which improved the solubility and prolonged cargo release. Then, E2@uECMNPs were further embedded into the thermosensitive aloe-poloxamer hydrogel (E2@uECMNPs/AP). Multiple components from E2@uECMNPs/AP system could collectively promote proliferation and inhibit apoptosis of endometrial stromal cells. E2@uECMNPs/AP significantly increased morphological recovery and decreased uterine fibrosis rate compared with IUA rats in other groups in vivo. Additionally, the levels of Ki67, cytokeratin, and estrogen receptor β were all up-regulated, along with the decreased expression of TGF-β1 and TNF-α in the uterus from rats receiving E2@uECMNPs/AP therapy. Taken together, in situ administration of E2@uECMNPs/AP hydrogel could effectively promote endometrial regeneration and prevent the re-adhesion.

Muscone/RI7217 co-modified upward messenger DTX liposomes enhanced permeability of blood-brain barrier and targeting glioma

Rationale: The dual-targeted drug delivery system was designed for enhancing permeation of the blood-brain barrier (BBB) and providing an anti-glioma effect. As transferrin receptor (TfR) is over-expressed by the brain capillary endothelial (hCMEC/D3) and glioma cells, a mouse monoclonal antibody, RI7217, with high affinity and selectivity for TfR, was used to study the brain targeted drug delivery system. Muscone, an ingredient of traditional Chinese medicine (TCM) musk, was used as the "guide" drug to probe the permeability of the BBB for drug delivery into the cerebrospinal fluid. This study investigated the combined effects of TCM aromatic resuscitation and modern receptor-targeted technology by the use of muscone/RI7217 co-modified docetaxel (DTX) liposomes for enhanced drug delivery to the brain for anti-glioma effect. Methods: Cellular drug uptake from the formulations was determined using fluorescence microscopy and flow cytometry. The drug penetrating ability into tumor spheroids were visualized using confocal laser scanning microscopy (CLSM). In vivo glioma-targeting ability of formulations was evaluated using whole-body fluorescent imaging system. The survival curve study was performed to evaluate the anti-glioma effect of the formulations. Results: The results showed that muscone and RI7217 co-modified DTX liposomes enhanced uptake into both hCMEC/D3 and U87-MG cells, increased penetration to the deep region of U87-MG tumor spheroids, improved brain targeting in vivo and prolonged survival time of nude mice bearing tumor. Conclusion: Muscone and RI7217 co-modified DTX liposomes were found to show improved brain targeting and enhanced the efficacy of anti-glioma drug treatment in vivo.

3D cultures for modeling nanomaterial-based photothermal therapy

Photothermal therapy (PTT) is one of the most promising techniques for cancer tumor ablation. Nanoparticles are increasingly being investigated for use with PTT and can serve as theranostic agents. Based on the ability of near-infrared nano-photo-absorbers to generate heat under laser irradiation, PTT could prove advantageous in certain situations over more classical cancer therapies. To analyze the efficacy of nanoparticle-based PTT, preclinical in vitro studies typically use 2D cultures, but this method cannot completely mimic the complex tumor organization, bioactivity, and physiology that all control the complex penetration depth, biodistribution, and tissue diffusion parameters of nanomaterials in vivo. To fill this knowledge gap, 3D culture systems have been explored for PTT analysis. These models provide more realistic microenvironments that allow spatiotemporal oxygen gradients and cancer cell adaptations to be considered. This review highlights the work that has been done to advance 3D models for cancer microenvironment modeling, specifically in the context of advanced, functionalized nanoparticle-directed PTT.

Recent development and biomedical applications of decellularized extracellular matrix biomaterials

Decellularized matrix (dECM) is isolated extracellular matrix of tissues from its original inhabiting cells, which has emerged as a promising natural biomaterial for tissue engineering, aiming at support, replacement or regeneration of damaged tissues. The dECM can be easily obtained from tissues/organs of various species by adequate decellularization methods, and mimics the structure and composition of the native extracellular matrix, providing a favorable cellular environment. In this review, we summarize the recent developments in the preparation of dECM materials, including decellularization, crosslinking and sterilization. Also, we cover the advances in the utilization of dECM biomaterials in regeneration medicine in pre-clinic and clinical trials. Moreover, we highlight those emerging medical benefits of dECM beyond tissue engineering, such as cell transplantation, in vitro/in vivo model and therapeutic cues delivery. With the advances in the preparation and broader application, the dECM biomaterials could become the gold scaffold and pharmaceutical excipients in medical sciences.

Design, synthesis and biological evaluation of chalcone analogues with novel dual antioxidant mechanisms as potential anti-ischemic stroke agents

Scavenging reactive oxygen species (ROS) by antioxidants is the important therapy to cerebral ischemia-reperfusion injury (CIRI) in stroke. The antioxidant with novel dual-antioxidant mechanism of directly scavenging ROS and indirectly through antioxidant pathway activation may be a promising CIRI therapeutic strategy. In our study, a series of chalcone analogues were designed and synthesized, and multiple potential chalcone analogues with dual antioxidant mechanisms were screened. Among these compounds, the most active 33 not only conferred cytoprotection of H2O2-induced oxidative damage in PC12 cells through scavenging free radicals directly and activating NRF2/ARE antioxidant pathway at the same time, but also played an important role against ischemia/reperfusion-related brain injury in animals. More importantly, in comparison with mono-antioxidant mechanism compounds, 33 exhibited higher cytoprotective and neuroprotective potential in vitro and in vivo. Overall, our findings showed compound 33 could emerge as a promising anti-ischemic stroke drug candidate and provided novel dual-antioxidant mechanism strategies and concepts for oxidative stress-related diseases treatment.

Selenium Enhances the Apoptotic Efficacy of Docetaxel Through Activation of TRPM2 Channel in DBTRG Glioblastoma Cells

The rate of mitosis of cancer cells is significantly higher than normal primary cells with increased metabolic needs, which in turn enhances the generation of reactive oxygen species (ROS) production. Higher ROS production is known to increase cancer cell dependence on ROS scavenging systems to counteract the increased ROS. Therapeutic options which selectively modulate the levels of intracellular ROS in cancers are likely candidates for drug discovery. Docetaxel (DTX) has demonstrated antitumor activity in preclinical and clinical studies. It is thought that DTX induces cell death through excessive ROS production and increased Ca²⁺ entry. The Ca²⁺ permeable TRPM2 channel is activated by ROS. Selenium (Se) has been previously used to stimulate apoptosis for the treatment of glioblastoma cells resistant to DTX. However, the potential mechanism(s) of the additive effect of DTX on TRPM2 channels in cancer cells remains unclear. The aim of this study was to evaluate the effect of combination therapy of DTX and Se on activation of TRPM2 in DBTRG glioblastoma cells. DBTRG cells were divided into four treatment groups: control, DTX (10 nM for 10 h), Se (1 μM for 10 h), and DTX+Se. Our study showed that apoptosis (Annexin V and propidium iodide), mitochondrial membrane depolarization (JC1), and ROS production levels were increased in DBTRG cells following treatment with Se and DTX respectively. Cell number and viability, and the levels of apoptosis, JC1, ROS, and [Ca²⁺]_i, induced by DTX, were further increased following addition of Se. We also observed an additive increase in the activation of the NAD-dependent DNA repair enzyme poly (ADP-ribose) polymerase-1 (PARP-1) activity, which was accompanied by a decline in its essential substrate NAD⁺. As well, the Se- and DTX-induced increases in intracellular Ca²⁺ florescence intensity were decreased following treatment with the TRPM2 antagonist N-(p-amylcinnamoyl) anthranilic acid (ACA). Therefore, combination therapy with Se and DTX may represent an effective strategy for the treatment of glioblastoma cells and may be associated with TRPM2-mediated increases in oxidative stress and [Ca²⁺]_i.

Inducing a Transient Increase in Blood-Brain Barrier Permeability for Improved Liposomal Drug Therapy of Glioblastoma Multiforme

The blood-brain barrier (BBB) selectively controls the passage of endogenous and exogenous molecules between systemic circulation and the brain parenchyma. Nanocarrier-based drugs such as liposomes and nanoparticles are an attractive prospect for cancer therapy since they can carry a drug payload and be modified to improve targeting and retention at the desired site. However, the BBB prevents most therapeutic drugs from entering the brain, including physically restricting the passage of liposomes and nanoparticles. In this paper, we show that a low dose of systemically injected recombinant human vascular endothelial growth factor induces a short period of increased BBB permeability. We have shown increased delivery of a range of nanomedicines to the brain including contrast agents for imaging, varying sizes of nanoparticles, small molecule chemotherapeutics, tracer dyes, and liposomal chemotherapeutics. However, this effect was not uniform across all brain regions, and permeability varied depending on the drug or molecule measured. We have found that this window of BBB permeability effect is transient, with normal BBB integrity restored within 4 h. This strategy, combined with liposomal doxorubicin, was able to significantly extend survival in a mouse model of human glioblastoma. We have found no evidence of systemic toxicity, and the technique was replicated in pigs, demonstrating that this technique could be scaled up and potentially be translated to the clinic, thus allowing the use of nanocarrier-based therapies for brain disorders.

Ratiometric delivery of two therapeutic candidates with inherently dissimilar physicochemical property through pH-sensitive core-shell nanoparticles targeting the heterogeneous tumor cells of glioma

Currently, combination drug therapy is one of the most effective approaches to glioma treatment. However, due to the inherent dissimilar pharmacokinetics of individual drugs and blood brain barriers, it was difficult for the concomitant drugs to simultaneously be delivered to glioma in an optimal dose ratio manner. Herein, a cationic micellar core (Cur-M) was first prepared from d-α-tocopherol-grafted-ε-polylysine polymer to encapsulate the hydrophobic curcumin, followed by dopamine-modified-poly-γ-glutamic acid polymer further deposited on its surface as a anion shell through pH-sensitive linkage to encapsulate the hydrophilic doxorubicin (DOX) hydrochloride. By controlling the combinational Cur/DOX molar ratio at 3:1, a pH-sensitive core-shell nanoparticle (PDCP-NP) was constructed to simultaneously target the cancer stem cells (CSCs) and the differentiated tumor cells. PDCP-NP exhibited a dynamic diameter of 160.8 nm and a zeta-potential of -30.5 mV, while its core-shell structure was further confirmed by XPS and TEM. The ratiometric delivery capability of PDCP-NP was confirmed by in vitro and in vivo studies, in comparison with the cocktail Cur/DOX solution. Meanwhile, the percentage of CSCs in tumors was significantly decreased from 4.16% to 0.95% after treatment with PDCP-NP. Overall, PDCP-NP may be a promising carrier for the combination therapy with drug candidates having dissimilar physicochemical properties.

Incorporation of nanoparticles into transplantable decellularized matrices: Applications and challenges

Decellularization of tissues can significantly improve regenerative medicine and tissue engineering by producing natural, less immunogenic, three-dimensional, acellular matrices with high biological activity for transplantation. Decellularized matrices retain specific critical components of native tissues such as stem cell niche, various growth factors, and the ability to regenerate in vivo. However, recellularization and functionalization of these matrices remain limited, highlighting the need to improve the characteristics of decellularized matrices. Incorporating nanoparticles into decellularized tissues can overcome these limitations because nanoparticles possess unique properties such as multifunctionality and can modify the surface of decellularized matrices with additional growth factors, which can be loaded onto the nanoparticles. Therefore, in this minireview, we highlight the various approaches used to improve decellularized matrices with incorporation of nanoparticles and the challenges present in these applications.

Endogenous pH-responsive nanoparticles with programmable size changes for targeted tumor therapy and imaging applications

Nanotechnology-based antitumor drug delivery systems, known as nanocarriers, have demonstrated their efficacy in recent years. Typically, the size of the nanocarriers is around 100 nm. It is imperative to achieve an optimum size of these nanocarriers which must be designed uniquely for each type of delivery process. For pH-responsive nanocarriers with programmable size, changes in pH (~6.5 for tumor tissue, ~5.5 for endosomes, and ~5.0 for lysosomes) may serve as an endogenous stimulus improving the safety and therapeutic efficacy of antitumor drugs. This review focuses on current advanced pH-responsive nanocarriers with programmable size changes for anticancer drug delivery. In particular, pH-responsive mechanisms for nanocarrier retention at tumor sites, size reduction for penetrating into tumor parenchyma, escaping from endo/lysosomes, and swelling or disassembly for drug release will be highlighted. Additional trends and challenges of employing these nanocarriers in future clinical applications are also addressed.

Size shrinkable drug delivery nanosystems and priming the tumor microenvironment for deep intratumoral penetration of nanoparticles

The penetration of nanomedicine into solid tumor still constitutes a great challenge for cancer therapy, which lead to the failure of thorough clearance of tumor cells. Aiming at solving this issue, lots of encouraging progress has been made in the development of multistage nanoparticles triggered by various stimuli in the past few years. Besides, the therapeutical effects of nanoagents are also greatly impacted by the complex tumor microenvironment, and remodeling tumor microenvironment has become another important approach for promoting nanoparticles penetration. In this review, we summarize and analyze recent research progress and challenges in promoting nanoparticle penetration based on two kinds of different strategies, which include size shrinkable nanoparticles and priming tumor microenvironments. Especially, many recent reported multi-strategy approaches based on particle size reduction in conjugated with other therapeutic strategies are discussed. And we expect to provide some useful enlightenments and proposals on nanotechnology-based drug delivery systems for more effective therapy of solid tumors.

Multicellular Tumor Spheroids (MCTS) as a 3D In Vitro Evaluation Tool of Nanoparticles

Multicellular tumor spheroid models (MCTS) are often coined as 3D in vitro models that can mimic the microenvironment of tissues. MCTS have gained increasing interest in the nano-biotechnology field as they can provide easily accessible information on the performance of nanoparticles without using animal models. Considering that many countries have put restrictions on animals testing, which will only tighten in the future as seen by the recent developments in the Netherlands, 3D models will become an even more valuable tool. Here, an overview on MCTS is provided, focusing on their use in cancer research as most nanoparticles are tested in MCTS for treatment of primary tumors. Thereafter, various types of nanoparticles-from self-assembled block copolymers to inorganic nanoparticles, are discussed. A range of physicochemical parameters including the size, shape, surface chemistry, ligands attachment, stability, and stiffness are found to influence nanoparticles in MCTS. Some of these studies are complemented by animal studies confirming that lessons from MCTS can in part predict the behaviour in vivo. In summary, MCTS are suitable models to gain additional information on nanoparticles. While not being able to replace in vivo studies, they can bridge the gap between traditional 2D in vitro studies and in vivo models.

Drug delivery to solid tumors: the predictive value of the multicellular tumor spheroid model for nanomedicine screening

The increasing number of publications on the subject shows that nanomedicine is an attractive field for investigations aiming to considerably improve anticancer chemotherapy. Based on selective tumor targeting while sparing healthy tissue, carrier-mediated drug delivery has been expected to provide significant benefits to patients. However, despite reduced systemic toxicity, most nanodrugs approved for clinical use have been less effective than previously anticipated. The gap between experimental results and clinical outcomes demonstrates the necessity to perform comprehensive drug screening by using powerful preclinical models. In this context, in vitro three-dimensional models can provide key information on drug behavior inside the tumor tissue. The multicellular tumor spheroid (MCTS) model closely mimics a small avascular tumor with the presence of proliferative cells surrounding quiescent cells and a necrotic core. Oxygen, pH and nutrient gradients are similar to those of solid tumor. Furthermore, extracellular matrix (ECM) components and stromal cells can be embedded in the most sophisticated spheroid design. All these elements together with the physicochemical properties of nanoparticles (NPs) play a key role in drug transport, and therefore, the MCTS model is appropriate to assess the ability of NP to penetrate the tumor tissue. This review presents recent developments in MCTS models for a better comprehension of the interactions between NPs and tumor components that affect tumor drug delivery. MCTS is particularly suitable for the high-throughput screening of new nanodrugs.

Skin-penetrating polymeric nanoparticles incorporated in silk fibroin hydrogel for topical delivery of curcumin to improve its therapeutic effect on psoriasis mouse model

A poor percutaneous penetration capability for most topical anti-inflammatory drugs is one of the main causes compromising their therapeutic effects on psoriatic skin. Even though curcumin has shown a remarkable efficacy in the treatment of psoriasis, its effective penetration through the stratum corneum is still a major challenge during transdermal delivery. The aim of our study was to design skin-permeating nanoparticles (NPs) to facilitate delivery of curcumin to the deeper layers of the skin. A novel amphiphilic polymer, RRR-α-tocopheryl succinate-grafted-ε-polylysine conjugate (VES-g-ε-PLL) was synthesized and self-assembled into polymeric nanoparticles. The nanoparticles of VES-g-ε-PLL exhibiting an ultra-small hydrodynamic diameter (24.4nm) and a positive Zeta potential (19.6mV) provided a strong skin-penetrating ability in vivo. Moreover, curcumin could effectively be encapsulated in the polymeric nanoparticles with a drug loading capacity of 3.49% and an encapsulating efficiency of 78.45%. In order to prolong the retention time of the ultra-small curcumin-loaded nanoparticles (CUR-NPs) in the skin, silk fibroin was used as a hydrogel-based matrix to further facilitate topical delivery of the model drug. In vitro studies showed that CUR-NPs incorporated in silk fibroin hydrogel (CUR-NPs-gel) exhibited a slower release profile of curcumin than the plain CUR-gel, without compromising the skin penetration ability of CUR-NPs. In vivo studies on miquimod-induced psoriatic mice showed that CUR-NPs-gel exhibited a higher therapeutic effect than CUR-NPs as the former demonstrated a more powerful skin-permeating capability and a more effective anti-keratinization process. CUR-NPs-gel was therefore able to inhibit the expression of inflammatory cytokines (TNF-α, NF-κB and IL-6) to a greater extent. In conclusion, the permeable nanoparticle-gel system may be a potential carrier for the topical delivery of lipophilic anti-psoriatic drugs.

Nanomaterials for convection-enhanced delivery of agents to treat brain tumors

Nanomaterials represent a promising and versatile platform for the delivery of therapeutics to the brain. Treatment of brain tumors has been a long-standing challenge in the field of neuro-oncology. The current standard of care - a multimodal approach of surgery, radiation and chemotherapy - yields only a modest therapeutic benefit for patients with malignant gliomas. A major obstacle for treatment is the failure to achieve sufficient delivery of therapeutics at the tumor site. Recent advances in local drug delivery techniques, along with the development of highly effective brain-penetrating nanocarriers, have significantly improved treatment and imaging of brain tumors in preclinical studies. The major advantage of this combined strategy is the ability to optimize local therapy, by maintaining an effective and sustained concentration of therapeutics in the brain with minimal systemic toxicity. This review highlights some of the latest developments, significant advancements and current challenges in local delivery of nanomaterials for the treatment of brain tumors.

Folic acid-decorated polyamidoamine dendrimer exhibits high tumor uptake and sustained highly localized retention in solid tumors: Its utility for local siRNA delivery

The utility of folic acid (FA)-decorated polyamidoamine dendrimer G4 (G4-FA) as a vector was investigated for local delivery of siRNA. In a xenograft HN12 (or HN12-YFP) tumor mouse model of head and neck squamous cell carcinomas (HNSCC), intratumorally (i.t.) injected G4-FA exhibited high tumor uptake and sustained highly localized retention in the tumors according to near infrared (NIR) imaging assessment. siRNA against vascular endothelial growth factor A (siVEGFA) was chosen as a therapeutic modality. Compared to the nontherapeutic treatment groups (PBS solution or dendrimer complexed with nontherapeutic siRNA against green fluorescent protein (siGFP)), G4-FA/siVEGFA showed tumor inhibition effects in single-dose and two-dose regimen studies. In particular, two doses of G4-FA/siVEGFA i.t. administered eight days apart resulted in a more profound inhibition of tumor growth, accompanied with significant reduction in angiogenesis, as judged by CD31 staining and microvessel counts. Tumor size reduction in the two-dose regimen study was ascertained semi-quantitatively by live fluorescence imaging of YFP tumors and independently supported antitumor effects of G4-FA/siVEGFA. Taken together, G4-FA shows high tumor uptake and sustained retention properties, making it a suitable platform for local delivery of siRNAs to treat cancers that are readily accessible such as HNSCC.

STATEMENT OF SIGNIFICANCE

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and is difficult to transfect for gene therapy. We developed folate receptor (FR)-targeted polyamidoamine (PAMAM) dendrimer for enhanced delivery of genes to HNSCC and gained in-depth understanding of how gene delivery and transfection in head and neck squamous cancer cells can be enhanced via FR-targeted PAMAM dendrimers. The results we report here are encouraging and present latest advances in using dendrimers for cancer therapies, in particular for HNSCC. Our work has demonstrated that localized delivery of FR-targeted PAMAM dendrimer G4 complexed with siVEGFA resulted in pronounced tumor suppression in an HN12 xenograft tumor model. Tumor suppression was attributed to enhanced tumor uptake of siRNA and prolonged nanoparticle retention in the tumor. Taken together, G4-FA shows high tumor uptake and sustained highly localized retention properties, making it a suitable platform for local delivery of siRNAs to treat cancers that are readily accessible such as HNSCC.

A Thermosensitive Heparin-Poloxamer Hydrogel Bridges aFGF to Treat Spinal Cord Injury

Acidic fibroblast growth factor (aFGF) exerts a protective effect on spinal cord injury (SCI) but is limited by the lack of physicochemical stability and the ability to cross the blood spinal cord barrier (BSCB). As promising biomaterials, hydrogels contain substantial amounts of water and a three-dimensional porous structure and are commonly used to load and deliver growth factors. Heparin can not only enhance growth factor loading onto hydrogels but also can stabilize the structure and control the release behavior. Herein, a novel aFGF-loaded thermosensitive heparin-poloxamer (aFGF-HP) hydrogel was developed and applied to provide protection and regeneration after SCI. To assess the effects of the aFGF-HP hydrogel, BSCB restoration, neuron and axonal rehabilitation, glial scar inhibition, inflammatory response suppression, and motor recovery were studied both in vivo and in vitro. The aFGF-HP hydrogels exhibited sustained release of aFGF and protected the bioactivity of aFGF in vitro. Compared to groups intravenously administered either drug-free HP hydrogel or aFGF alone, the aFGF-HP hydrogel group revealed prominent and attenuated disruption of the BSCB, reduced neuronal apoptosis, reactive astrogliosis, and increased neuron and axonal rehabilitation both in vivo and in vitro. This work provides an effective approach to enhance recovery after SCI and provide a successful strategy for SCI protection.

Enhanced neuroprotection with decellularized brain extracellular matrix containing bFGF after intracerebral transplantation in Parkinson's disease rat model

Extracellular matrix-based biomaterials have many advantages over synthetic polymer materials for regenerative medicine applications. In central nervous system (CNS), basic fibroblast growth factor (bFGF) is widely studied as a potential agent for Parkinson's disease (PD). However, the poor stability of bFGF hampered its clinical use. In this study, CNS-derived biologic scaffold containing bFGF was used to enhance and extend the neuroprotective effect of bFGF on PD targeted therapy. Decellularized brain extracellular matrix (dcBECM) was prepared by chemical extraction. The biocompatibility of dcBECM was evaluated using CCK-8 assay and magnetic resonance imaging (MRI). The controlled-release behavior of dcBECM containing bFGF (bFGF+dcBECM) was confirmed by ELISA assay. Furthermore, the cytocompatibility and neuroprotective effect of bFGF+dcBECM was evaluated in vitro and in vivo. From results, dcBECM showed a three-dimensional network structure with high biocompatibility. MRI of dcBECM implanted rats showed nearly seamless fusion of dcBECM with the adjoining tissues. The cumulative release rate of bFGF+dcBECM in vitro reached to 75.88% at 10h and maintained sustained release trend during the observation. ELISA results in vivo further confirmed the sustained-release behavior (from 12h to 3d) of bFGF+dcBECM in brain tissues. Among the experimental groups, bFGF+dcBECM group showed the highest cell survival rate of PD model cells, improved behavioral recovery and positive expressions of neurotrophic proteins in PD recovered rats. In conclusion, sustained neuroprotection in PD rats was achieved by using bFGF+dcBECM. The combination of dcBECM and bFGF would be a promising therapeutic strategy to realize an effective and safe alternative for CNS disease treatment.