Expansion of Ovarian Cancer Stem-like Cells in Poly(ethylene glycol)-Cross-Linked Poly(methyl vinyl ether-alt-maleic acid) and Alginate Double-Network Hydrogels

Deciphering the "Rosetta Stone" of ovarian cancer stem cells: Opportunities and challenges

Ovarian cancer stem cells (OCSCs) play a pivotal role in the initiation, maintenance, and progression of ovarian cancer, functioning through complex molecular mechanisms that are closely linked to metastasis and drug resistance. The complexity of these underlying mechanisms contributes to cancer hallmarks such as the high plasticity of OCSCs, leading to chemotherapy resistance; activation of invasion and metastasis, epigenetic reprogramming, and cell death resistance; and deregulation of cellular metabolism. OCSCs are characterized by the expression of markers including ALDH, CD133, CD44, and CD24. They preserve their stemness through intricate molecular mechanisms that involve interactions with the tumor microenvironment and various signaling pathways. To investigate these molecular mechanisms, both in vitro and in vivo models of OCSC have been established. The results of these studies can be applied in clinical practice, facilitating the development of various new therapies. This review aims to provide a deeper understanding of the mechanisms through which OCSCs function, highlighting significant opportunities for future research aimed at improving ovarian cancer treatment.

SKOV-3 Cell Aggregates on a Microfluidic Chip with a Thermoresponsive Hydrogel as a Culture Scaffold for DOX Assessment

Microfluidic chip technology is very popular in life sciences. Here, ovarian cancer SKOV-3 cell aggregates were formed using thermoresponsive poly(N-isopropylacrylamide-co-acrylic acid) (PNA) hydrogel as a culture scaffold on a microfluidic chip serving as an operating platform. A simple microfluidic chip was designed and fabricated as the three-dimensional (3D) cell culture microplatform. Different concentrations of doxorubicin (DOX) were fed to the obtained SKOV-3 cell aggregates on the chip via a pump. All characterization results indicated that this system could effectively perform 3D cell culture and drug evaluation to a certain extent. In addition, by grafting the RGD sequence, the biocompatibility of the PNA hydrogel was improved. On the one hand, the grafting of the RGD sequence into the hydrogel could significantly improve cell proliferation in this system; on the other hand, it led to an earlier appearance of DOX drug resistance. This versatile model in this study has the potential for further use in in vitro human ovarian cancer physiological models, drug discovery, and toxicology research.

Potential of natural polysaccharide for ovarian cancer therapy

Ovarian cancer, characterized by high lethality, presents a significant clinical challenge. The standard first-line treatment is surgery and chemotherapy; however, postoperative chemotherapy is often ineffective and associated with severe side effects and the development of drug resistance. Consequently, there is an urgent need for innovative drug delivery strategies to enhance therapeutic efficacy. Natural polysaccharide polymers with high bioactivity have been extensively investigated for use alone or as adjuvants to chemotherapy and radiotherapy, and also for the preparation of efficient delivery systems for ovarian cancer therapy. This paper aims to review recent advances in the application of natural polysaccharides, including hyaluronic acid, chitosan, alginate, and cellulose, in the therapy of ovarian cancer. This paper primarily discusses the anti-tumor properties inherent to these natural polysaccharide polymers and offers a summary of their role in delivery systems used in ovarian cancer therapy.

Application of hydrogels for targeting cancer stem cells in cancer treatment

Cancer stem cells (CSCs) are a major hindrance to clinical cancer treatment. Owing to their high tumorigenic and metastatic potential, CSCs are vital in malignant tumor initiation, growth, metastasis, and therapeutic resistance, leading to tumorigenesis and recurrence. Compared with normal tumor cells, CSCs express high levels of surface markers (CD44, CD90, CD133, etc.) and activate specific signaling pathways (Wnt/β-catenin, Notch, and Hedgehog). Although Current drug delivery systems (DDS) precisely target CSCs, the heterogeneity and multidrug resistance of CSCs impede CSC isolation and screening. Conversely, hydrogel DDSs exhibit good biocompatibility and high drug delivery efficiency. Hydrogels are three-dimensional (3D) spatial structures for drug encapsulation that facilitate the controlled release of bioactive molecules. Hence, hydrogels can be loaded with drugs to precisely target CSCs. Their 3D structure can also culture non-CSCs and facilitate their transformation into CSCs. for identification and isolation. Given that their elastic modulus and stiffness characteristics reflect those of the cellular microenvironment, hydrogels can simulate extracellular matrix pathways and markers to regulate CSCs, disrupting the equilibrium between CSC and non-CSC transformation. This article reviews the CSC microenvironment, metabolism, signaling pathway, and surface markers. Additionally, we summarize the existing CSC targeting strategies and explore the application of hydrogels for CSC screening and treatment. Finally, we discuss potential advances in CSC research that may lead to curative measures for tumors through targeted and precise attacks on CSCs.

Recent advances in double network hydrogels based on naturally-derived polymers: synthesis, properties, and biological applications

Hydrogels composed of naturally-derived biopolymers have garnered significant research interest due to the bioavailability and biocompatibility of starting materials. However, translating these advantages to practical use is challenged by limitations of mechanical properties and stability of the resulting materials. The development of double network (DN) hydrogels has led to greatly enhanced mechanical properties and shows promise toward broadening the applications of conventional synthetic or natural hydrogels. This review highlights recently developed protein-based and polysaccharide-based DN hydrogels. For each biopolymer, we focus on a subset of DN hydrogels centered around a theme related to synthetic design or applications. Network structures and crosslinking mechanisms that endow enhanced mechanical properties and performance to the materials are discussed. Important applications, including tissue engineering, drug delivery, bioadhesives, wound healing, and wearable sensors, that arise from the inherent properties of the natural polymer or its combination with other materials are also emphasized. Finally, we discuss ongoing challenges to stimulate the discovery of new design principles for the future of DN hydrogels based on naturally-derived polymers for biological applications.

A Comprehensive Assessment on the Pivotal Role of Hydrogels in Scaffold-Based Bioprinting

The past a few decades have seen exponential growth in the field of regenerative medicine. What began as extirpative (complete tissue or organ removal), with little regard to the effects of tissue loss and/or disfigurement, has evolved towards fabricating engineered tissues using personalized living cells (e.g., stem cells), and customizing a matrix or structural organization to support and guide tissue development. Biofabrication, largely accomplished through three-dimensional (3D) printing technology, provides precise, controlled, and layered assemblies of cells and biomaterials, emulating the heterogenous microenvironment of the in vivo tissue architecture. This review provides a concise framework for the bio-manufacturing process and addresses the contributions of hydrogels to biological modeling. The versatility of hydrogels in bioprinting is detailed along with an extensive elaboration of their physical, mechanical, and biological properties, as well as their assets and limitations in bioprinting. The scope of various hydrogels in tissue formation has been discussed through the case studies of biofabricated 3D constructs in order to provide the readers with a glimpse into the barrier-breaking accomplishments of biomedical sciences. In the end, the restraints of bioprinting itself are discussed, accompanied with the identification of available engineering strategies to overcome them.

Polymeric Hydrogels for In Vitro 3D Ovarian Cancer Modeling

Ovarian cancer (OC) grows and interacts constantly with a complex microenvironment, in which immune cells, fibroblasts, blood vessels, signal molecules and the extracellular matrix (ECM) coexist. This heterogeneous environment provides structural and biochemical support to the surrounding cells and undergoes constant and dynamic remodeling that actively promotes tumor initiation, progression, and metastasis. Despite the fact that traditional 2D cell culture systems have led to relevant medical advances in cancer research, 3D cell culture models could open new possibilities for the development of an in vitro tumor microenvironment more closely reproducing that observed in vivo. The implementation of materials science and technology into cancer research has enabled significant progress in the study of cancer progression and drug screening, through the development of polymeric scaffold-based 3D models closely recapitulating the physiopathological features of native tumor tissue. This article provides an overview of state-of-the-art in vitro tumor models with a particular focus on 3D OC cell culture in pre-clinical studies. The most representative OC models described in the literature are presented with a focus on hydrogel-based scaffolds, which guarantee soft tissue-like physical properties as well as a suitable 3D microenvironment for cell growth. Hydrogel-forming polymers of either natural or synthetic origin investigated in this context are described by highlighting their source of extraction, physical-chemical properties, and application for 3D ovarian cancer cell culture.

Advances in hydrogel-based vascularized tissues for tissue repair and drug screening

The construction of biomimetic vasculatures within the artificial tissue models or organs is highly required for conveying nutrients, oxygen, and waste products, for improving the survival of engineered tissues in vitro. In recent times, the remarkable progress in utilizing hydrogels and understanding vascular biology have enabled the creation of three-dimensional (3D) tissues and organs composed of highly complex vascular systems. In this review, we give an emphasis on the utilization of hydrogels and their advantages in the vascularization of tissues. Initially, the significance of vascular elements and the regeneration mechanisms of vascularization, including angiogenesis and vasculogenesis, are briefly introduced. Further, we highlight the importance and advantages of hydrogels as artificial microenvironments in fabricating vascularized tissues or organs, in terms of tunable physical properties, high similarity in physiological environments, and alternative shaping mechanisms, among others. Furthermore, we discuss the utilization of such hydrogels-based vascularized tissues in various applications, including tissue regeneration, drug screening, and organ-on-chips. Finally, we put forward the key challenges, including multifunctionalities of hydrogels, selection of suitable cell phenotype, sophisticated engineering techniques, and clinical translation behind the development of the tissues with complex vasculatures towards their future development.

Three-Dimensional Modelling of Ovarian Cancer: From Cell Lines to Organoids for Discovery and Personalized Medicine

Ovarian cancer has the highest mortality of all of the gynecological malignancies. There are several distinct histotypes of this malignancy characterized by specific molecular events and clinical behavior. These histotypes have differing responses to platinum-based drugs that have been the mainstay of therapy for ovarian cancer for decades. For histotypes that initially respond to a chemotherapeutic regime of carboplatin and paclitaxel such as high-grade serous ovarian cancer, the development of chemoresistance is common and underpins incurable disease. Recent discoveries have led to the clinical use of PARP (poly ADP ribose polymerase) inhibitors for ovarian cancers defective in homologous recombination repair, as well as the anti-angiogenic bevacizumab. While predictive molecular testing involving identification of a genomic scar and/or the presence of germline or somatic BRCA1 or BRCA2 mutation are in clinical use to inform the likely success of a PARP inhibitor, no similar tests are available to identify women likely to respond to bevacizumab. Functional tests to predict patient response to any drug are, in fact, essentially absent from clinical care. New drugs are needed to treat ovarian cancer. In this review, we discuss applications to address the currently unmet need of developing physiologically relevant in vitro and ex vivo models of ovarian cancer for fundamental discovery science, and personalized medicine approaches. Traditional two-dimensional (2D) in vitro cell culture of ovarian cancer lacks critical cell-to-cell interactions afforded by culture in three-dimensions. Additionally, modelling interactions with the tumor microenvironment, including the surface of organs in the peritoneal cavity that support metastatic growth of ovarian cancer, will improve the power of these models. Being able to reliably grow primary tumoroid cultures of ovarian cancer will improve the ability to recapitulate tumor heterogeneity. Three-dimensional (3D) modelling systems, from cell lines to organoid or tumoroid cultures, represent enhanced starting points from which improved translational outcomes for women with ovarian cancer will emerge.

Crucial roles of graphene oxide in preparing alginate/nanofibrillated cellulose double network composites hydrogels

In this study, a novel strategy to prepare sodium alginate (SA)/nano fibrillated cellulose (NFC) double network (DN) hydrogel beads with the aid of graphene oxide (GO) was developed. In comparison with the multi-step freezing-thawing method, this study employs a facile one-step freeze drying method with the presence of GO sheets. The crucial roles of GO were highlighted as an efficient nucleating agent of NFC and a reinforcer for the hydrogel. The adsorption property of the DN hydrogel towards crystal violet (CV) was also studied. Results indicated that the introduction of GO could greatly facilitate the formation of double networks. Furthermore, the as-prepared DN hydrogel beads exhibited an efficacious adsorption property towards CV. The maximum adsorption capacity of the hydrogels for CV was observed as 665 mg g^-1. Therefore, our approach here represents a facile method for the preparation of crystalline polymer based DN hydrogels to replace the awkward freezing-thawing process, giving inspiration for DN hydrogels design and preparation. Moreover, due to its efficient adsorption capacity, the hydrogels hold great promise for the water pollution control materials.