Cryogel-supported stem cell factory for customized sustained release of bispecific antibodies for cancer immunotherapy

Unveiling the functional roles of patient-derived tumour organoids in assessing the tumour microenvironment and immunotherapy

Recent studies have established the pivotal roles of patient-derived tumour organoids (PDTOs), innovative three-dimensional (3D) culture systems, in various biological and medical applications. PDTOs, as promising tools, have been established and extensively used for drug screening, prediction of immune response and assessment of immunotherapeutic effectiveness in various cancer types, including glioma, ovarian cancer and so on. The overarching goal is to facilitate the translation of new therapeutic modalities to guide personalised immunotherapy. Notably, there has been a recent surge of interest in the co-culture of PDTOs with immune cells to investigate the dynamic interactions between tumour cells and immune microenvironment. A comprehensive and in-depth investigation is necessary to enhance our understanding of PDTOs as promising testing platforms for cancer immunotherapy. This review mainly focuses on the latest updates on the applications and challenges of PDTO-based methods in anti-cancer immune responses. We strive to provide a comprehensive understanding of the potential and prospects of PDTO-based technologies as next-generation strategies for advancing immunotherapy approaches.

Role of Mesenchymal Stem/Stromal Cells in Head and Neck Cancer-Regulatory Mechanisms of Tumorigenic and Immune Activity, Chemotherapy Resistance, and Therapeutic Benefits of Stromal Cell-Based Pharmacological Strategies

Head and neck cancer (HNC) entails a heterogenous neoplastic disease that arises from the mucosal epithelium of the upper respiratory system and the gastrointestinal tract. It is characterized by high morbidity and mortality, being the eighth most common cancer worldwide. It is believed that the mesenchymal/stem stromal cells (MSCs) present in the tumour milieu play a key role in the modulation of tumour initiation, development and patient outcomes; they also influence the resistance to cisplatin-based chemotherapy, the gold standard for advanced HNC. MSCs are multipotent, heterogeneous and mobile cells. Although no MSC-specific markers exist, they can be recognized based on several others, such as CD73, CD90 and CD105, while lacking the presence of CD45, CD34, CD14 or CD11b, CD79α, or CD19 and HLA-DR antigens; they share phenotypic similarity with stromal cells and their capacity to differentiate into other cell types. In the tumour niche, MSC populations are characterized by cell quiescence, self-renewal capacity, low reactive oxygen species production and the acquisition of epithelial-to-mesenchymal transition properties. They may play a key role in the process of acquiring drug resistance and thus in treatment failure. The present narrative review examines the links between MSCs and HNC, as well as the different mechanisms involved in the development of resistance to current chemo-radiotherapies in HNC. It also examines the possibilities of pharmacological targeting of stemness-related chemoresistance in HNSCC. It describes promising new strategies to optimize chemoradiotherapy, with the potential to personalize patient treatment approaches, and highlights future therapeutic perspectives in HNC.

Mesenchymal Stem Cells in Myelodysplastic Syndromes and Leukaemia

Mesenchymal stem cells (MSCs) are one of the main residents in the bone marrow (BM) and have an essential role in the regulation of haematopoietic stem cell (HSC) differentiation and proliferation. Myelodysplastic syndromes (MDSs) are a group of myeloid disorders impacting haematopoietic stem and progenitor cells (HSCPs) that are characterised by BM failure, ineffective haematopoiesis, cytopenia, and a high risk of transformation through the expansion of MDS clones together with additional genetic defects. It has been indicated that MSCs play anti-tumorigenic roles such as in cell cycle arrest and pro-tumorigenic roles including the induction of metastasis in MDS and leukaemia. Growing evidence has shown that MSCs have impaired functions in MDS, such as decreased proliferation capacity, differentiation ability, haematopoiesis support, and immunomodulation function and increased inflammatory alterations within the BM through some intracellular pathways such as Notch and Wnt and extracellular modulators abnormally secreted by MSCs, including increased expression of inflammatory factors and decreased expression of haematopoietic factors, contributing to the development and progression of MDSs. Therefore, MSCs can be targeted for the treatment of MDSs and leukaemia. However, it remains unclear what drives MSCs to behave abnormally. In this review, dysregulations in MSCs and their contributions to myeloid haematological malignancies will be discussed.

Nanotechnology and bioengineering approaches to improve the potency of mesenchymal stem cell as an off-the-shelf versatile tumor delivery vehicle

Targeting actionable mutations in oncogene-driven cancers and the evolution of immuno-oncology are the two prominent revolutions that have influenced cancer treatment paradigms and caused the emergence of precision oncology. However, intertumoral and intratumoral heterogeneity are the main challenges in both fields of precision cancer treatment. In other words, finding a universal marker or pathway in patients suffering from a particular type of cancer is challenging. Therefore, targeting a single hallmark or pathway with a single targeted therapeutic will not be efficient for fighting against tumor heterogeneity. Mesenchymal stem cells (MSCs) possess favorable characteristics for cellular therapy, including their hypoimmune nature, inherent tumor-tropism property, straightforward isolation, and multilineage differentiation potential. MSCs can be loaded with various chemotherapeutics and oncolytic viruses. The combination of these intrinsic features with the possibility of genetic manipulation makes them a versatile tumor delivery vehicle that can be used for in vivo selective tumor delivery of various chemotherapeutic and biological therapeutics. MSCs can be used as biofactory for the local production of chemical or biological anticancer agents at the tumor site. MSC-mediated immunotherapy could facilitate the sustained release of immunotherapeutic agents specifically at the tumor site, and allow for the achievement of therapeutic concentrations without the need for repetitive systemic administration of high therapeutic doses. Despite the enthusiasm evoked by preclinical studies that used MSC in various cancer therapy approaches, the translation of MSCs into clinical applications has faced serious challenges. This manuscript, with a critical viewpoint, reviewed the preclinical and clinical studies that have evaluated MSCs as a selective tumor delivery tool in various cancer therapy approaches, including gene therapy, immunotherapy, and chemotherapy. Then, the novel nanotechnology and bioengineering approaches that can improve the potency of MSC for tumor targeting and overcoming challenges related to their low localization at the tumor sites are discussed.

Engineered Bio-Based Hydrogels for Cancer Immunotherapy

Immunotherapy represents a revolutionary paradigm in cancer management, showcasing its potential to impede tumor metastasis and recurrence. Nonetheless, challenges including limited therapeutic efficacy and severe immune-related side effects are frequently encountered, especially in solid tumors. Hydrogels, a class of versatile materials featuring well-hydrated structures widely used in biomedicine, offer a promising platform for encapsulating and releasing small molecule drugs, biomacromolecules, and cells in a controlled manner. Immunomodulatory hydrogels present a unique capability for augmenting immune activation and mitigating systemic toxicity through encapsulation of multiple components and localized administration. Notably, hydrogels based on biopolymers have gained significant interest owing to their biocompatibility, environmental friendliness, and ease of production. This review delves into the recent advances in bio-based hydrogels in cancer immunotherapy and synergistic combinatorial approaches, highlighting their diverse applications. It is anticipated that this review will guide the rational design of hydrogels in the field of cancer immunotherapy, fostering clinical translation and ultimately benefiting patients.

Evaluation of reproducible cryogel preparation based on automated image analysis using deep learning

Cryogels represent a class of porous sponge-like materials possessing unique properties including high-fidelity reproduction of tissue structure and maximized permeability. Their architecture is mainly based on an interconnected network of macropores that provides sufficient stability while allowing the movement of substances through the material. In most cryogel applications, the pore size is very important, especially when the material is used as a 3D scaffold for tissue culture, applied as a filter, or utilized as a membrane. In this study, poly(dimethylacrylamide-co-2-hydroxyethyl methacrylate) cryogels have been prepared by two preparation methods to investigate the reproducibility of homogeneous pore structures and pore sizes. Automated image analysis algorithms were developed to rapidly evaluate cryogel pore sizes based on scanning electron microscopy (SEM) images. The quantification approach contained a unique combination of classical and deep learning-based algorithms. To validate the accuracy of the two models, we compared the results obtained from automated SEM image analysis with those from manual pore size determinations and mercury intrusion porosimetry (MIP) measurements. Effect sizes were calculated to compare the results from manual and automated pore size measurements for the cryogel reproducibility series. 81% of the values obtained revealed only trivial differences, which strongly suggests that automated image analysis can reliably substitute the manual evaluation of cryogel pore sizes. The use of an adapted reactor setup yielded cryogels with heterogeneous morphologies in the absence of recognizable pore structures. With the conventional cryogel preparation using plastic syringes, the obtained cryogels represented highly reproducible morphologies and pore sizes in the range between 17 and 22 μm. Calculated effect sizes within the cryogel replicate series revealed only trivial differences between the obtained pore sizes in 83.5% or 99.4% of the data (classical approach and deep learning-based approach, respectively).

FLT3-directed UniCAR T-cell therapy of acute myeloid leukaemia

Adaptor chimeric antigen receptor (CAR) T-cell therapy offers solutions for improved safety and antigen escape, which represent main obstacles for the clinical translation of CAR T-cell therapy in myeloid malignancies. The adaptor CAR T-cell platform 'UniCAR' is currently under early clinical investigation. Recently, the first proof of concept of a well-tolerated, rapidly switchable, CD123-directed UniCAR T-cell product treating patients with acute myeloid leukaemia (AML) was reported. Relapsed and refractory AML is prone to high plasticity under therapy pressure targeting one single tumour antigen. Thus, targeting of multiple tumour antigens seems to be required to achieve durable anti-tumour responses, underlining the need to further design alternative AML-specific target modules (TM) for the UniCAR platform. We here present the preclinical development of a novel FMS-like tyrosine kinase 3 (FLT3)-directed UniCAR T-cell therapy, which is highly effective for in vitro killing of both AML cell lines and primary AML samples. Furthermore, we show in vivo functionality in a murine xenograft model. PET analyses further demonstrate a short serum half-life of FLT3 TMs, which will enable a rapid on/off switch of UniCAR T cells. Overall, the presented preclinical data encourage the further development and clinical translation of FLT3-specific UniCAR T cells for the therapy of AML.

Hydrogels for RNA delivery

RNA-based therapeutics have shown tremendous promise in disease intervention at the genetic level, and some have been approved for clinical use, including the recent COVID-19 messenger RNA vaccines. The clinical success of RNA therapy is largely dependent on the use of chemical modification, ligand conjugation or non-viral nanoparticles to improve RNA stability and facilitate intracellular delivery. Unlike molecular-level or nanoscale approaches, macroscopic hydrogels are soft, water-swollen three-dimensional structures that possess remarkable features such as biodegradability, tunable physiochemical properties and injectability, and recently they have attracted enormous attention for use in RNA therapy. Specifically, hydrogels can be engineered to exert precise spatiotemporal control over the release of RNA therapeutics, potentially minimizing systemic toxicity and enhancing in vivo efficacy. This Review provides a comprehensive overview of hydrogel loading of RNAs and hydrogel design for controlled release, highlights their biomedical applications and offers our perspectives on the opportunities and challenges in this exciting field of RNA delivery.

Cryogels: Advancing Biomaterials for Transformative Biomedical Applications

Cryogels, composed of synthetic and natural materials, have emerged as versatile biomaterials with applications in tissue engineering, controlled drug delivery, regenerative medicine, and therapeutics. However, optimizing cryogel properties, such as mechanical strength and release profiles, remains challenging. To advance the field, researchers are exploring advanced manufacturing techniques, biomimetic design, and addressing long-term stability. Combination therapies and drug delivery systems using cryogels show promise. In vivo evaluation and clinical trials are crucial for safety and efficacy. Overcoming practical challenges, including scalability, structural integrity, mass transfer constraints, biocompatibility, seamless integration, and cost-effectiveness, is essential. By addressing these challenges, cryogels can transform biomedical applications with innovative biomaterials.

Mesenchymal Stem Cells Derived from Umbilical Cord Blood having Excellent Stemness Properties with Therapeutic Benefits - a New Era in Cancer Treatment

Mesenchymal stem cells (MSCs) are the most promising candidates for cellular therapies, and most therapeutic applications have focused on MSCs produced from adult bone marrow, despite mounting evidence that MSCs are present in a wide range of conditions. Umbilical cord blood (UCB) is a valuable source of hematopoietic stem cells, but its therapeutic potential extends beyond the hematopoietic component, which also suggests solid organ regenerative potential. With potential ranging from embryonic-like to lineage-committed progenitor cells, many different stems and progenitor cell populations have been postulated. MSC is currently inferred by numerous clinical applications for human UCB. aAs stem cell therapy kicks off some new research and these cells show such a boon to stem cell therapy, it is nevertheless characteristic that the prospect of UCB conservation is gaining momentum. Taken together, the experience described here shows that MSCs derived from UCB are seen as attractive therapeutic candidates for various human disorders including cancer. It is argued that a therapeutic stem cell transplant, using stem cells from UCB, provides a reliable repository of early precursor cells that can be useful in a large number of different conditions, considering issues of safety, availability, transplant methodology, rejection, and side effects. In particular, we focus on the concept of isolation and expansion, comparing the phenotype with MSC derived from the UCB, describing the ability to differentiate, and lastly, the therapeutic potential concerning stromal support, stemness characteristic, immune modulation, and cancer stem cell therapy. Thus it is an overview of the therapeutic application of UCB derived MSCs, with a special emphasis on cancer. Besides, the current evidence on the double-edged sword of MSCs in cancer treatment and the latest advances in UCB-derived MSC in cancer research will be discussed.

Nanocarrier-hydrogel composite delivery systems for precision drug release

Hydrogels are a class of biomaterials widely implemented in medical applications due to their biocompatibility and biodegradability. Despite the many successes of hydrogel-based delivery systems, there remain challenges to hydrogel drug delivery such as a burst release at the time of administration, a limited ability to encapsulate certain types of drugs (i.e., hydrophobic drugs, proteins, antibodies, and nucleic acids), and poor tunability of geometry and shape for controlled drug release. This review discusses two main important advances in hydrogel fabrication for precision drug release: first, the incorporation of nanocarriers to diversify their drug loading capability, and second, the design of hydrogels using 3D printing to precisely control drug dosing and release kinetics via high-resolution structures and geometries. We also outline ongoing challenges and discuss opportunities to further optimize drug release from hydrogels for personalized medicine. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Leveraging biomaterials for enhancing T cell immunotherapy

The dynamic roles of T cells in the immune system to recognize and destroy the infected or mutated cells render T cell therapy a prospective treatment for a variety of diseases including cancer, autoimmune diseases, and allograft rejection. However, the clinical applications of T cell therapy remain unsatisfactory due to the tedious manufacturing process, off-target cytotoxicity, poor cell persistence, and associated adverse effects. To this end, various biomaterials have been introduced to enhance T cell therapy by facilitating proliferation, enhancing local enrichment, prolonging retention, and alleviating side effects. This review highlights the design strategies of biomaterials developed for T cell expansion, enrichment, and delivery as well as their corresponding therapeutic effects. The prospects of biomaterials for enhancing T cell immunotherapy are also discussed in this review.

New horizons of biomaterials in treatment of nerve damage in diabetes mellitus: A translational prospective review

BACKGROUND

Peripheral nerve injury is a serious concern that leads to loss of neuronal communication that impairs the quality of life and, in adverse conditions, causes permanent disability. The limited availability of autografts with associated demerits shifts the paradigm of researchers to use biomaterials as an alternative treatment approach to recover nerve damage.

PURPOSE

The purpose of this study is to explore the role of biomaterials in translational treatment approaches in diabetic neuropathy.

STUDY DESIGN

The present study is a prospective review study.

METHODS

Published literature on the role of biomaterials in therapeutics was searched for.

RESULTS

Biomaterials can be implemented with desired characteristics to overcome the problem of nerve regeneration. Biomaterials can be further exploited in the treatment of nerve damage especially associated with PDN. These can be modified, customized, and engineered as scaffolds with the potential of mimicking the extracellular matrix of nerve tissue along with axonal regeneration. Due to their beneficial biological deeds, they can expedite tissue repair and serve as carriers of cellular and pharmacological treatments. Therefore, the emerging research area of biomaterials-mediated treatment of nerve damage provides opportunities to explore them as translational biomedical treatment approaches.

CONCLUSIONS

Pre-clinical and clinical trials in this direction are needed to establish the effective role of several biomaterials in the treatment of other human diseases.

Engineering hyaluronic acid-based cryogels for CD44-mediated breast tumor reconstruction

Breast cancer is a major health concern worldwide and is the leading cause of cancer-related death among American women. Traditional therapies, such as surgery, chemotherapy, and radiotherapy, are usually ineffective. Furthermore, cancer recurrence following targeted therapy often results from acquired drug resistance. Therefore, more realistic tumor models than monolayer cell culture for drug screening and discovery in an in vitro setting would facilitate the development of new therapeutic strategies. Toward this goal, we first developed a simple, rapid, low-cost, and high-throughput method for generating uniform multi-cellular tumor spheroids (MCTS) with controllable size. Next, biomimetic cryogel scaffolds fabricated from hyaluronic acid (HA) were utilized as a platform to reconstruct breast tumor microtissues with aspects of the complex tumor microenvironment in three dimensions. Finally, we investigated the interactions between the HA-based cryogels and CD44-positive breast tumor cells, individually or as MCTS. We found that incorporating the adhesive RGD peptide in cryogels led to the formation of a monolayer of tumor cells on the polymer walls, whereas MCTS cultured on RGD-free HA cryogels resulted in the growth of large and dense microtumors, more similar to native tumor masses. As a result, the MCTS-laden HA cryogel system induced a highly aggressive and chemotherapy drug-resistant tumor model. RGD-free HA-based cryogels represent an effective starting point for designing tumor models for preclinical research, therapeutic drug screening, and early cancer diagnosis.

Targeting Brain Tumors with Mesenchymal Stem Cells in the Experimental Model of the Orthotopic Glioblastoma in Rats

Despite multimodal approaches for the treatment of multiforme glioblastoma (GBM) advances in outcome have been very modest indicating the necessity of novel diagnostic and therapeutic strategies. Currently, mesenchymal stem cells (MSCs) represent a promising platform for cell-based cancer therapies because of their tumor-tropism, low immunogenicity, easy accessibility, isolation procedure, and culturing. In the present study, we assessed the tumor-tropism and biodistribution of the superparamagnetic iron oxide nanoparticle (SPION)-labeled MSCs in the orthotopic model of C6 glioblastoma in Wistar rats. As shown in in vitro studies employing confocal microscopy, high-content quantitative image cytometer, and xCelligence system MSCs exhibit a high migratory capacity towards C6 glioblastoma cells. Intravenous administration of SPION-labeled MSCs in vivo resulted in intratumoral accumulation of the tagged cells in the tumor tissues that in turn significantly enhanced the contrast of the tumor when high-field magnetic resonance imaging was performed. Subsequent biodistribution studies employing highly sensitive nonlinear magnetic response measurements (NLR-M₂) supported by histological analysis confirm the retention of MSCs in the glioblastoma. In conclusion, MSCs due to their tumor-tropism could be employed as a drug-delivery platform for future theranostic approaches.

Localized delivery of immunotherapeutics: A rising trend in the field

Immunotherapy is becoming a new standard of care for multiple cancers, while several limitations are impending its further clinical success. Immunotherapeutic agents often have inappropriate pharmacokinetics on their own and/or exhibit limited specificity to tumor cells, leading to severe immuno-related adverse effects and limited efficacy. Suitable formulating strategies that confer prolonged contact with or efficient proliferation in tumors while reducing exposure to normal tissues are highly worthy to explore. With the assistance of biomaterial carriers, targeted therapy can be achieved artificially by implanting or injecting drug depots into desired sites, about which the wisdoms in literature have been rich. The relevant results have suggested a "local but systemic" effect, that is, local replenishment of immune modulators achieves a high treatment efficacy that also governs distant metastases, thereby building another rationale for localized delivery. Particularly, implantable scaffolds have been further engineered to recruit disseminated tumor cells with an efficiency high enough to reduce tumor burdens at typical metastatic organs, and simultaneously provide diagnostic signals. This review introduces recent advances in this emerging area along with a perspective on the opportunities and challenges in the way to clinical application.

Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing

Cryogels are macroporous polymeric structures formed from the cryogelation of monomers/polymers in a solvent below freezing temperature. Due to their inherent interconnected macroporosity, ease of preparation, and biocompatibility, they are increasingly being investigated for use in biomedical applications such as 3D-bioprinting, drug delivery, wound healing, and as injectable therapeutics. This review highlights the fundamentals of macroporous cryogel preparation, cryogel properties that can be useful in the highlighted biomedical applications, followed by a comprehensive review of recent studies in these areas. Research evaluated includes the use of cryogels to combat various types of cancer, for implantation without surgical incision, and use as highly effective wound dressings. Furthermore, conclusions and outlooks are discussed for the use of these promising and durable macroporous cryogels.

Customizing biohybrid cryogels to serve as ready-to-use delivery systems of signaling proteins

Macroporous cryogels have recently gained increasing interest for the controlled administration of signaling proteins in tissue engineering due to an advantageous combination of material properties. However, most of the previously reported cryogel systems did not allow for tunable, sustained protein release. We therefore designed a set of ready-to-use multi-armed polyethylene glycol (starPEG)-heparin cryogel systems containing different amounts of the protein-affine glycosaminoglycan component heparin to enable systematically tunable long-term delivery of different signaling proteins without affecting other cell-instructive properties. Experimental data and mathematical modeling indicate that the macroporous structure causes local differences in the concentration of proteins released into the pores and in the surrounding of the cryogels. As a proof-of-concept for their ready-to-use potential, cryogels pre-functionalized with signaling proteins and cell adhesion-peptides were demonstrated to induce the neuronal differentiation of colonizing pheochromocytoma cells. The elaborated approach opens up new perspectives for cryogels as easily storable and applicable systems for the precision delivery of signaling proteins.

Glycosaminoglycan-Based Cryogels as Scaffolds for Cell Cultivation and Tissue Regeneration

Cryogels are a class of macroporous, interconnective hydrogels polymerized at sub-zero temperatures forming mechanically robust, elastic networks. In this review, latest advances of cryogels containing mainly glycosaminoglycans (GAGs) or composites of GAGs and other natural or synthetic polymers are presented. Cryogels produced in this way correspond to the native extracellular matrix (ECM) in terms of both composition and molecular structure. Due to their specific structural feature and in addition to an excellent biocompatibility, GAG-based cryogels have several advantages over traditional GAG-hydrogels. This includes macroporous, interconnective pore structure, robust, elastic, and shape-memory-like mechanical behavior, as well as injectability for many GAG-based cryogels. After addressing the cryogelation process, the fabrication of GAG-based cryogels and known principles of GAG monomer crosslinking are discussed. Finally, an overview of specific GAG-based cryogels in biomedicine, mainly as polymeric scaffold material in tissue regeneration and tissue engineering-related controlled release of bioactive molecules and cells, is provided.

Tuning the network charge of biohybrid hydrogel matrices to modulate the release of SDF-1

The delivery of chemotactic signaling molecules via customized biomaterials can effectively guide the migration of cells to improve the regeneration of damaged or diseased tissues. Here, we present a novel biohybrid hydrogel system containing two different sulfated glycosaminoglycans (sGAG)/sGAG derivatives, namely either a mixture of short heparin polymers (Hep-Mal) or structurally defined nona-sulfated tetrahyaluronans (9s-HA4-SH), to precisely control the release of charged signaling molecules. The polymer networks are described in terms of their negative charge, i.e. the anionic sulfate groups on the saccharides, using two parameters, the integral density of negative charge and the local charge distribution (clustering) within the network. The modulation of both parameters was shown to govern the release characteristics of the chemotactic signaling molecule SDF-1 and allows for seamless transitions between burst and sustained release conditions as well as the precise control over the total amount of delivered protein. The obtained hydrogels with well-adjusted release profiles effectively promote MSC migration in vitro and emerge as promising candidates for new treatment modalities in the context of bone repair and wound healing.

Design and Assessment of Biodegradable Macroporous Cryogels as Advanced Tissue Engineering and Drug Carrying Materials

Cryogels obtained by the cryotropic gelation process are macroporous hydrogels with a well-developed system of interconnected pores and shape memory. There have been significant recent advancements in our understanding of the cryotropic gelation process, and in the relationship between components, their structure and the application of the cryogels obtained. As cryogels are one of the most promising hydrogel-based biomaterials, and this field has been advancing rapidly, this review focuses on the design of biodegradable cryogels as advanced biomaterials for drug delivery and tissue engineering. The selection of a biodegradable polymer is key to the development of modern biomaterials that mimic the biological environment and the properties of artificial tissue, and are at the same time capable of being safely degraded/metabolized without any side effects. The range of biodegradable polymers utilized for cryogel formation is overviewed, including biopolymers, synthetic polymers, polymer blends, and composites. The paper discusses a cryotropic gelation method as a tool for synthesis of hydrogel materials with large, interconnected pores and mechanical, physical, chemical and biological properties, adapted for targeted biomedical applications. The effect of the composition, cross-linker, freezing conditions, and the nature of the polymer on the morphology, mechanical properties and biodegradation of cryogels is discussed. The biodegradation of cryogels and its dependence on their production and composition is overviewed. Selected representative biomedical applications demonstrate how cryogel-based materials have been used in drug delivery, tissue engineering, regenerative medicine, cancer research, and sensing.

Reviewing the potential use of scaffold-mediated localized chemotherapy in oncology

Post-surgical recurrence and metastasis remain to be the major concern in oncology. The absence of any therapeutic modality during the interim period between the surgical intervention and initiation of conventional radiotherapy and chemotherapy allows the residual cancer cells to proliferate, culminating in recurrence and/or metastasis. Introducing a therapeutic modality during this interim period could suppress the proliferation of the residual tumor cells. Further, as the detrimental effects of conventional chemotherapy and radiotherapy drastically reduce the patient’s quality of life, use of therapeutic modality with localized effect can reduce the risk of systemic toxicity. Thus, the present manuscript reviews the potential use of scaffold-mediated local chemotherapy in oncology. Its localized effect would prevent systemic toxicity, while the scaffold serves as an ideal vehicle for the sustained targeted delivery of therapeutic agents.

Mesenchymal stem cells and cancer therapy: insights into targeting the tumour vasculature

A crosstalk established between tumor microenvironment and tumor cells leads to contribution or inhibition of tumor progression. Mesenchymal stem cells (MSCs) are critical cells that fundamentally participate in modulation of the tumor microenvironment, and have been reported to be able to regulate and determine the final destination of tumor cell. Conflicting functions have been attributed to the activity of MSCs in the tumor microenvironment; they can confer a tumorigenic or anti-tumor potential to the tumor cells. Nonetheless, MSCs have been associated with a potential to modulate the tumor microenvironment in favouring the suppression of cancer cells, and promising results have been reported from the preclinical as well as clinical studies. Among the favourable behaviours of MSCs, are releasing mediators (like exosomes) and their natural migrative potential to tumor sites, allowing efficient drug delivering and, thereby, efficient targeting of migrating tumor cells. Additionally, angiogenesis of tumor tissue has been characterized as a key feature of tumors for growth and metastasis. Upon introduction of first anti-angiogenic therapy by a monoclonal antibody, attentions have been drawn toward manipulation of angiogenesis as an attractive strategy for cancer therapy. After that, a wide effort has been put on improving the approaches for cancer therapy through interfering with tumor angiogenesis. In this article, we attempted to have an overview on recent findings with respect to promising potential of MSCs in cancer therapy and had emphasis on the implementing MSCs to improve them against the suppression of angiogenesis in tumor tissue, hence, impeding the tumor progression.

Understanding stem cells and its pivotal role in regenerative medicine

Stem cells (SCs) are clonogenic cells that develop into the specialized cells which later responsible for making up various types of tissue in the human body. SCs are not only the appropriate source of information for cell division, molecular and cellular processes, and tissue homeostasis but also one of the major putative biological aids to diagnose and cure various degenerative diseases. This study emphasises on various research outputs that occurred in the past two decades. This will give brief information on classification, differentiation, detection, and various isolation techniques of SCs. Here, the various signalling pathways which includes WNT, Sonic hedgehog, Notch, BMI1 and C-met pathways and how does it effect on the regeneration of various classes of SCs and factors that regulates the potency of the SCs are also been discussed. We also focused on the application of SCs in the area of regenerative medicine along with the cellular markers that are useful as salient diagnostic or curative tools or in both, by the process of reprogramming, which includes diabetes, cancer, cardiovascular disorders and neurological disorders. The biomarkers that are mentioned in various literatures and experiments include PDX1, FOXA2, HNF6, and NKX6-1 (for diabetes); CD33, CD24, CD133 (for cancer); c-Kit, SCA-1, Wilm's tumor 1 (for cardiovascular disorders); and OCT4, SOX2, c-MYC, EN1, DAT and VMAT2 (for neurological disorders). In this review, we come to know the advancements and scopes of potential SC-based therapies, its diverse applications in clinical fields that can be helpful in the near future.

Neurothreads: Development of supportive carriers for mature dopaminergic neuron differentiation and implantation

In this study we present the use of elastic macroporous cryogels for differentiation and transplantation of mature neurons. We develop a coating suitable for long-term neuronal culture, including stem cell differentiation, by covalent immobilization of neural adhesion proteins. In the context of cell therapy for Parkinson's disease, we show compatibility with established dopaminergic differentiation of both immortalized mesencephalic progenitors - LUHMES - and human embryonic stem cells (hESCs). We adjust structural properties of the biomaterial to create carriers - Neurothreads - favourable for cell viability during transplantation. Finally, we show feasibility of preservation of mature neurons, supported by Neurothreads, one month after in-vivo transplantation. Preliminary data suggests that the Neurothread approach could provide more mature and less proliferative cells in vivo.

Guest-host interlinked PEG-MAL granular hydrogels as an engineered cellular microenvironment

We report the development of a polyethylene glycol (PEG) hydrogel scaffold that provides the advantages of conventional bulk PEG hydrogels for engineering cellular microenvironments and allows for rapid cell migration. PEG microgels were used to assemble a densely packed granular system with an intrinsic interstitium-like negative space. In this material, guest-host molecular interactions provide reversible non-covalent linkages between discrete PEG microgel particles to form a cohesive bulk material. In guest-host chemistry, different guest molecules reversibly and non-covalently interact with their cyclic host molecules. Two species of PEG microgels were made, each with one functional group at the end of the four arm PEG-MAL functionalized using thiol click chemistry. The first was functionalized with the host molecule β-cyclodextrin, a cyclic oligosaccharide of repeating d-glucose units, and the other functionalized with the guest molecule adamantane. These two species provide a reversible guest-host interaction between microgel particles when mixed, generating an interlinked network with a percolated interstitium. We showed that this granular configuration, unlike conventional bulk PEG hydrogels, enabled the rapid migration of THP-1 monocyte cells. The guest-host microgels also exhibited shear-thinning behavior, providing a unique advantage over current bulk PEG hydrogels.

Preparation of lysozyme loaded gelatin microcryogels and investigation of their antibacterial properties

Antibacterial micron-sized cryogels, so-called microcryogels, were prepared by cryogelation of gelatin and integration of lysozyme. Gelation yield, specific surface area, macro-porosity and swelling degree of the microcryogels were examined in order to characterize their physical properties. MTT method was utilized to measure cell viability of the gelatin microcryogels with a period of 24, 48, and 72 h and no significant decrease was observed at 72 h. Apoptotic staining assay also showed high viability at 24, 48, 72 h in parallel with the control group. The antibacterial performances of the gelatin microcryogels against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli were examined. The results showed that the incorporation of lysozyme into gelatin microcryogels exhibited the antibacterial activity against S. aureus, B. subtilis, and E. coli, that may provide great potential for various applications in the biomedical industry.

Versatile chimeric antigen receptor platform for controllable and combinatorial T cell therapy

Chimeric antigen receptor (CAR) T cells show remarkable therapeutic effects in some hematological malignancies. However, CAR T cells can also cause life-threatening side effects. In order to minimize off-target and on-target/off-tumor reactions, improve safety, enable controllability, provide high flexibility, and increase tumor specificity, we established a novel humanized artificial receptor platform termed RevCARs. RevCAR genes encode for small surface receptors lacking any antigen-binding moiety. Steering of RevCAR T cells occurs via bispecific targeting molecules (TMs). The small size of RevCAR-encoding genes allows the construction of polycistronic vectors. Here, we demonstrate that RevCAR T cells efficiently kill tumor cells, can be steered by TMs, flexibly redirected against multiple targets, and used for combinatorial targeting following the "OR" and "AND" gate logic.

New directions in chimeric antigen receptor T cell [CAR-T] therapy and related flow cytometry

Chimeric antigen receptor (CAR) T cells provide a promising approach to the treatment of hematologic malignancies and solid tumors. Flow cytometry is a powerful analytical modality, which plays an expanding role in all stages of CAR T therapy, from lymphocyte collection, to CAR T cell manufacturing, to in vivo monitoring of the infused cells and evaluation of their function in the tumor environment. Therefore, a thorough understanding of the new directions is important for designing and implementing CAR T-related flow cytometry assays in the clinical and investigational settings. However, the speed of new discoveries and the multitude of clinical and preclinical trials make it challenging to keep up to date in this complex field. In this review, we summarize the current state of CAR T therapy, highlight the areas of emergent research, discuss applications of flow cytometry in modern cell therapy, and touch upon several considerations particular to CAR detection and assessing the effectiveness of CAR T therapy.

Biomaterials for Personalized Cell Therapy

Cell therapy has already had an important impact on healthcare and provided new treatments for previously intractable diseases. Notable examples include mesenchymal stem cells for tissue regeneration, islet transplantation for diabetes treatment, and T cell delivery for cancer immunotherapy. Biomaterials have the potential to extend the therapeutic impact of cell therapies by serving as carriers that provide 3D organization and support cell viability and function. With the growing emphasis on personalized medicine, cell therapies hold great potential for their ability to sense and respond to the biology of an individual patient. These therapies can be further personalized through the use of patient-specific cells or with precision biomaterials to guide cellular activity in response to the needs of each patient. Here, the role of biomaterials for applications in tissue regeneration, therapeutic protein delivery, and cancer immunotherapy is reviewed, with a focus on progress in engineering material properties and functionalities for personalized cell therapies.

Harnessing T Cells to Target Pediatric Acute Myeloid Leukemia: CARs, BiTEs, and Beyond

Outcomes for pediatric patients with acute myeloid leukemia (AML) remain poor, highlighting the need for improved targeted therapies. Building on the success of CD19-directed immune therapy for acute lymphocytic leukemia (ALL), efforts are ongoing to develop similar strategies for AML. Identifying target antigens for AML is challenging because of the high expression overlap in hematopoietic cells and normal tissues. Despite this, CD123 and CD33 antigen targeted therapies, among others, have emerged as promising candidates. In this review we focus on AML-specific T cell engaging bispecific antibodies and chimeric antigen receptor (CAR) T cells. We review antigens being explored for T cell-based immunotherapy in AML, describe the landscape of clinical trials upcoming for bispecific antibodies and CAR T cells, and highlight strategies to overcome additional challenges facing translation of T cell-based immunotherapy for AML.

Therapeutic Potential of Mesenchymal Stem Cells for Cancer Therapy

Mesenchymal stem cells (MSCs) are among the most frequently used cell type for regenerative medicine. A large number of studies have shown the beneficial effects of MSC-based therapies to treat different pathologies, including neurological disorders, cardiac ischemia, diabetes, and bone and cartilage diseases. However, the therapeutic potential of MSCs in cancer is still controversial. While some studies indicate that MSCs may contribute to cancer pathogenesis, emerging data reported the suppressive effects of MSCs on cancer cells. Because of this reality, a sustained effort to understand when MSCs promote or suppress tumor development is needed before planning a MSC-based therapy for cancer. Herein, we provide an overview on the therapeutic application of MSCs for regenerative medicine and the processes that orchestrates tissue repair, with a special emphasis placed on cancer, including central nervous system tumors. Furthermore, we will discuss the current evidence regarding the double-edged sword of MSCs in oncological treatment and the latest advances in MSC-based anti-cancer agent delivery systems.

T cell immunotherapy enhanced by designer biomaterials

Cancer immunotherapy has recently burst onto the center stage of cancer treatment and research. T lymphocyte adoptive cellular transfer (ACT), a form of cancer immunotherapy, has spawned unprecedented complete remissions for terminal patients with certain leukemias and lymphomas. Unfortunately, the successes have been overshadowed by the disappointing clinical results of ACT administered to treat solid tumors, in addition to the toxicities associated with the treatment, a lack of efficacy in a significant proportion of the patient population, and cancer relapse following the treatment. Biomaterials hold the promise of addressing these shortcomings. ACT consists of two main stages - T lymphocyte ex vivo expansion followed by reinfusion into the patient - and biomaterials can improve the efficacy of ACT at both stages. In this review, we highlight recent advances in the use of biomaterials for T lymphocyte adoptive cellular cancer immunotherapy and discuss the challenges at each stage.

The UniCAR system: A modular CAR T cell approach to improve the safety of CAR T cells

The idea to eliminate tumor cells via our own immune system is more than a hundred years old. However, a real break through came first with the development of check point inhibitors, bispecific antibodies (bsAbs) and T cells genetically modified to express Chimeric Antigen Receptors (CARs). Eventhough the clinical application of T cells equipped with CARs can lead to a complete remission, unfortunately, their application can also cause severe or even life threatening side effects as their activity can no more be adjusted once given to the patient. For targeting of tumor cells expressing tumor associated antigens (TAAs) which are not limited to tumor cells but also accessible on healthy tissues CAR T cells should not be permanently in a killing mode but be equipped with some kind of a switch whereby the activity of CAR T cells can reversely be turned "on and off ". Moreover, in case of cytokine release syndrome (CRS), tumor lysis syndrome (TLS), or other deadly side effects the possibility of an emergency shut down of the CAR T cell activity should exist. Modular CAR variants such as the UniCAR system may fulfill these requirements.

Preparation and Properties of Cryogel Based on Poly(2-hydroxyethyl methacrylate- co-glycidyl methacrylate)

The immobilized metal affinity cryogels based on poly(2-hydroxyethyl methacrylate- co-glycidyl methacrylate) (p(HEMA-GMA)) containing hydroxy and epoxy groups were prepared by free-radical copolymerization under cryogenic condition and then functionalized with iminodiacetic acid and chelated Cu²⁺, Ca²⁺, and Fe³⁺ ions to the p(HEMA-GMA) cryogel. The structures of p(HEMA-GMA) and immobilized metal-affinity cryogels were analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy. SEM results showed that the prepared cryogels had interconnected pores with the size of 30-100 μm. The performance of water swelling into the cryogels was fitted in Fickian diffusion. The adsorption property of cryogels was influenced by the immobilized ionic type, temperature, and adsorbate. The adsorption capacity of immobilized Cu²⁺ cryogel (p(HEMA)-Cu²⁺ (0.5 M) cryogel) was the highest in comparison with that of Ca²⁺ and Fe³⁺ affinity cryogels under the same condition. The maximum adsorption capacity of p(HEMA)-Cu²⁺ (0.5 M) cryogel for porcine pancreatic lipase was 150.14 mg/g at a higher temperature of 35 °C, whereas for bovine serum albumin, the maximum adsorption capacity was 154.11 mg/g at a lower temperature of 25 °C. The research of thermodynamics and kinetics indicated that the mechanism of the protein adsorption process corresponded to the Langmuir model and pseudo-second-order model.

Osteogenic Effects of VEGF-Overexpressed Human Adipose-Derived Stem Cells with Whitlockite Reinforced Cryogel for Bone Regeneration

Bone is a vascularized tissue that is comprised of collagen fibers and calcium phosphate crystals such as hydroxyapatite (HAp) and whitlockite (WH). HAp and WH are known to elicit bone regeneration by stimulating osteoblast activities and osteogenic commitment of stem cells. In addition, vascular endothelial growth factor (VEGF) is shown to promote osteogenesis and angiogenesis which is considered as an essential process in bone repair by providing nutrients. In this study, VEGF-secreting human adipose-derived stem cells (VEGF-ADSCs) are developed by transducing ADSCs with VEGF-encoded lentivirus. Additionally, WH-reinforced gelatin/heparin cryogels (WH-C) are fabricated by loading WH into gelatin/heparin cryogels. VEGF-ADSC secrete tenfold more VEGF than ADSC and show increased VEGF secretion with cell growth. Also, incorporation of WH into cryogels provides a mineralized environment with ions secreted from WH. When the VEGF-ADSCs are seeded on WH-C, sustained release of VEGF is observed due to the specific affinity of VEGF to heparin. Finally, the synergistic effect of VEGF-ADSC and WH on osteogenesis is successfully confirmed by alkaline phosphatase and real-time polymerase chain reaction analysis. In vivo bone formation is demonstrated via implantation of VEGF-ADSC seeded WH-C into mouse calvarial bone defect model, resulted in enhanced bone development with the highest bone volume/total volume.

Review: Synthetic scaffolds to control the biochemical, mechanical, and geometrical environment of stem cell-derived brain organoids

Stem cell-derived brain organoids provide a powerful platform for systematic studies of tissue functional architecture and the development of personalized therapies. Here, we review key advances at the interface of soft matter and stem cell biology on synthetic alternatives to extracellular matrices. We emphasize recent biomaterial-based strategies that have been proven advantageous towards optimizing organoid growth and controlling the geometrical, biomechanical, and biochemical properties of the organoid's three-dimensional environment. We highlight systems that have the potential to increase the translational value of region-specific brain organoid models suitable for different types of manipulations and high-throughput applications.

Three-Dimensional In Vitro Hydro- and Cryogel-Based Cell-Culture Models for the Study of Breast-Cancer Metastasis to Bone

Bone is the most common site for breast-cancer invasion and metastasis, and it causes severe morbidity and mortality. A greater understanding of the mechanisms leading to bone-specific metastasis could improve therapeutic strategies and thus improve patient survival. While three-dimensional in vitro culture models provide valuable tools to investigate distinct heterocellular and environmental interactions, sophisticated organ-specific metastasis models are lacking. Previous models used to investigate breast-to-bone metastasis have relied on 2.5D or singular-scaffold methods, constraining the in situ mimicry of in vitro models. Glycosaminoglycan-based gels have demonstrated outstanding potential for tumor-engineering applications. Here, we developed advanced biphasic in vitro microenvironments that mimic breast-tumor tissue (MCF-7 and MDA-MB-231 in a hydrogel) spatially separated with a mineralized bone construct (human primary osteoblasts in a cryogel). These models allow distinct advantages over former models due to the ability to observe and manipulate cellular migration towards a bone construct. The gels allow for the binding of adhesion-mediating peptides and controlled release of signaling molecules. Moreover, mechanical and architectural properties can be tuned to manipulate cell function. These results demonstrate the utility of these biomimetic microenvironment models to investigate heterotypic cell⁻cell and cell⁻matrix communications in cancer migration to bone.

Biopolymers for Antitumor Implantable Drug Delivery Systems: Recent Advances and Future Outlook

In spite of remarkable improvements in cancer treatments and survivorship, cancer still remains as one of the major causes of death worldwide. Although current standards of care provide encouraging results, they still cause severe systemic toxicity and also fail in preventing recurrence of the disease. In order to address these issues, biomaterial-based implantable drug delivery systems (DDSs) have emerged as promising therapeutic platforms, which allow local administration of drugs directly to the tumor site. Owing to the unique properties of biopolymers, they have been used in a variety of ways to institute biodegradable implantable DDSs that exert precise spatiotemporal control over the release of therapeutic drug. Here, the most recent advances in biopolymer-based DDSs for suppressing tumor growth and preventing tumor recurrence are reviewed. Novel emerging biopolymers as well as cutting-edge polymeric microdevices deployed as implantable antitumor DDSs are discussed. Finally, a review of a new therapeutic modality within the field, which is based on implantable biopolymeric DDSs, is given.

In situ forming injectable hydrogels for drug delivery and wound repair

Hydrogels have been utilized in regenerative applications for many decades because of their biocompatibility and similarity in structure to the native extracellular matrix. Initially, these materials were formed outside of the patient and implanted using invasive surgical techniques. However, advances in synthetic chemistry and materials science have now provided researchers with a library of techniques whereby hydrogel formation can occur in situ upon delivery through standard needles. This provides an avenue to minimally invasively deliver therapeutic payloads, fill complex tissue defects, and induce the regeneration of damaged portions of the body. In this review, we highlight these injectable therapeutic hydrogel biomaterials in the context of drug delivery and tissue regeneration for skin wound repair.

Immunoengineering with biomaterials for enhanced cancer immunotherapy

Cancer immunotherapy has recently shown dramatic clinical success inducing durable response in patients of a wide variety of malignancies. Further improvement of the clinical outcome with immune related cancer treatment requests more exquisite manipulation of a patient's immune system with increased immunity against diseases while mitigating the toxicities. To meet this challenge, biomaterials applied to immunoengineering are being developed to achieve tissue- and/or cell-specific immunomodulation and thus could potentially enhance both the efficacy and safety of current cancer immunotherapies. Here, we review the recent advancement in the field of immunoengineering using biomaterials and their applications in promoting different modalities of cancer immunotherapies, with focus on cell-, antibody-, immunomodulator-, and gene-based immune related treatments and their combinations with conventional therapies. Challenges and opportunities are discussed in applying biomaterials engineering strategies in the development of future cancer immunotherapies. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Retargeting of UniCAR T cells with an in vivo synthesized target module directed against CD19 positive tumor cells

Recent treatments of leukemias with T cells expressing chimeric antigen receptors (CARs) underline their impressive therapeutic potential but also their risk of severe side effects including cytokine release storms and tumor lysis syndrome. In case of cross-reactivities, CAR T cells may also attack healthy tissues. To overcome these limitations, we previously established a switchable CAR platform technology termed UniCAR. UniCARs are not directed against typical tumor-associated antigens (TAAs) but instead against a unique peptide epitope: Fusion of this peptide epitope to a recombinant antibody domain results in a target module (TM). TMs can cross-link UniCAR T cells with tumor cells and thereby lead to their destruction. So far, we constructed TMs with a short half-life. The fast turnover of such a TM allows to rapidly interrupt the treatment in case severe side effects occur. After elimination of most of the tumor cells, however, longer lasting TMs which have not to be applied via continous infusion would be more convenient for the patient. Here we describe and characterize a TM for retargeting UniCAR T cells to CD19 positive tumor cells. Moreover, we show that the TM can efficiently be produced in vivo from producer cells housed in a sponge-like biomimetic cryogel and, thereby, serving as an in vivo TM factory for an extended retargeting of UniCAR T cells to CD19 positive leukemic cells.