Isolation and characterization of type IV procollagen, laminin, and heparan sulfate proteoglycan from the EHS sarcoma

Human liver organoids: From generation to applications

In the last decade, research into human hepatology has been revolutionized by the development of mini human livers in a dish. These liver organoids are formed by self-organizing stem cells and resemble their native counterparts in cellular content, multicellular architecture, and functional features. Liver organoids can be derived from the liver tissue or pluripotent stem cells generated from a skin biopsy, blood cells, or renal epithelial cells present in urine. With the development of liver organoids, a large part of previous hurdles in modeling the human liver is likely to be solved, enabling possibilities to better model liver disease, improve (personalized) drug testing, and advance bioengineering options. In this review, we address strategies to generate and use organoids in human liver disease modeling, followed by a discussion of their potential application in drug development and therapeutics, as well as their strengths and limitations.

Methodology and Characterization of a 3D Bone Organoid Model Derived from Murine Cells

Here, we report on the development of a cost-effective, well-characterized three-dimensional (3D) model of bone homeostasis derived from commonly available stocks of immortalized murine cell lines and laboratory reagents. This 3D murine-cell-derived bone organoid model (3D-mcBOM) is adaptable to a range of contexts and can be used in conjunction with surrogates of osteoblast and osteoclast function to study cellular and molecular mechanisms that affect bone homeostasis in vitro or to augment in vivo models of physiology or disease. The 3D-mcBOM was established using a pre-osteoblast murine cell line, which was seeded into a hydrogel extracellular matrix (ECM) and differentiated into functional osteoblasts (OBs). The OBs mineralized the hydrogel ECM, leading to the deposition and consolidation of hydroxyapatite into bone-like organoids. Fourier-transform infrared (FTIR) spectroscopy confirmed that the mineralized matrix formed in the 3D-mcBOM was bone. The histological staining of 3D-mcBOM samples indicated a consistent rate of ECM mineralization. Type I collagen C-telopeptide (CTX1) analysis was used to evaluate the dynamics of OC differentiation and activity. Reliable 3D models of bone formation and homeostasis align with current ethical trends to reduce the use of animal models. This functional model of bone homeostasis provides a cost-effective model system using immortalized cell lines and easily procured supplemental compounds, which can be assessed by measuring surrogates of OB and OC function to study the effects of various stimuli in future experimental evaluations of bone homeostasis.

"Small Hepatocytes" in the Liver

Mature hepatocytes (MHs) in an adult rodent liver are categorized into the following three subpopulations based on their proliferative capability: type I cells (MH-I), which are committed progenitor cells that possess a high growth capability and basal hepatocytic functions; type II cells (MH-II), which possess a limited proliferative capability; and type III cells (MH-III), which lose the ability to divide (replicative senescence) and reach the final differentiated state. These subpopulations may explain the liver's development and growth after birth. Generally, small-sized hepatocytes emerge in mammal livers. The cells are characterized by being morphologically identical to hepatocytes except for their size, which is substantially smaller than that of ordinary MHs. We initially discovered small hepatocytes (SHs) in the primary culture of rat hepatocytes. We believe that SHs are derived from MH-I and play a role as hepatocytic progenitors to supply MHs. The population of MH-I (SHs) is distributed in the whole lobules, a part of which possesses a self-renewal capability, and decreases with age. Conversely, injured livers of experimental models and clinical cases showed the emergence of SHs. Studies demonstrate the involvement of SHs in liver regeneration. SHs that appeared in the injured livers are not a pure population but a mixture of two distinct origins, MH-derived and hepatic-stem-cell-derived cells. The predominant cell-derived SHs depend on the proliferative capability of the remaining MHs after the injury. This review will focus on the SHs that appeared in the liver and discuss the significance of SHs in liver regeneration.

New Solutions for Old Problems: How Reproductive Tissue Engineering Has Been Revolutionizing Reproductive Medicine

Acquired disorders and congenital defects of the male and female reproductive systems can have profound impacts on patients, causing sexual and endocrine dysfunction and infertility, as well as psychosocial consequences that affect their self-esteem, identity, sexuality, and relationships. Reproductive tissue engineering (REPROTEN) is a promising approach to restore fertility and improve the quality of life of patients with reproductive disorders by developing, replacing, or regenerating cells, tissues, and organs from the reproductive and urinary systems. In this review, we explore the latest advancements in REPROTEN techniques and their applications for addressing degenerative conditions in male and female reproductive organs. We discuss current research and clinical outcomes and highlight the potential of 3D constructs utilizing biomaterials such as scaffolds, cells, and biologically active molecules. Our review offers a comprehensive guide for researchers and clinicians, providing insights into how to reestablish reproductive tissue structure and function using innovative surgical approaches and biomaterials. We highlight the benefits of REPROTEN for patients, including preservation of fertility and hormonal production, reconstruction of uterine and cervical structures, and restoration of sexual and urinary functions. Despite significant progress, REPROTEN still faces ethical and technical challenges that need to be addressed. Our review underscores the importance of continued research in this field to advance the development of effective and safe REPROTEN approaches for patients with reproductive disorders.

Organoid Culture Development for Skeletal Systems

Organoids are widely considered to be ideal in vitro models that have been widely applied in many fields, including regenerative medicine, disease research and drug screening. It is distinguished from other three-dimensional in vitro culture model systems by self-organization and sustainability in long-term culture. The three core components of organoid culture are cells, exogenous factors, and culture matrix. Due to the complexity of bone tissue, and heterogeneity of osteogenic stem/progenitor cells, it is challenging to construct organoids for modeling skeletal systems. In this study, we examine current progress in the development of skeletal system organoid culture systems and analyze the current research status of skeletal stem cells, their microenvironmental factors, and various potential organoid culture matrix candidates to provide cues for future research trajectory in this field. Impact Statement The emergence of organoids has brought new opportunities for the development of many biomedical fields. The bone organoid field still has much room for exploration. This review discusses the characteristics distinguishing organoids from other three-dimensional model systems and examines current progress in the organoid production of skeletal systems. In addition, based on core elements of organoid cultures, three main problems that need to be solved in bone organoid generation are further analyzed. These include the heterogeneity of skeletal stem cells, their microenvironmental factors, and potential organoid culture matrix candidates. This information provides direction for the future research of bone organoids.

Using Biosensors to Study Organoids, Spheroids and Organs-on-a-Chip: A Mechanobiology Perspective

The increasing popularity of 3D cell culture models is being driven by the demand for more in vivo-like conditions with which to study the biochemistry and biomechanics of numerous biological processes in health and disease. Spheroids and organoids are 3D culture platforms that self-assemble and regenerate from stem cells, tissue progenitor cells or cell lines, and that show great potential for studying tissue development and regeneration. Organ-on-a-chip approaches can be used to achieve spatiotemporal control over the biochemical and biomechanical signals that promote tissue growth and differentiation. These 3D model systems can be engineered to serve as disease models and used for drug screens. While culture methods have been developed to support these 3D structures, challenges remain to completely recapitulate the cell-cell and cell-matrix biomechanical interactions occurring in vivo. Understanding how forces influence the functions of cells in these 3D systems will require precise tools to measure such forces, as well as a better understanding of the mechanobiology of cell-cell and cell-matrix interactions. Biosensors will prove powerful for measuring forces in both of these contexts, thereby leading to a better understanding of how mechanical forces influence biological systems at the cellular and tissue levels. Here, we discussed how biosensors and mechanobiological research can be coupled to develop accurate, physiologically relevant 3D tissue models to study tissue development, function, malfunction in disease, and avenues for disease intervention.

Considerations for modelling diffuse high-grade gliomas and developing clinically relevant therapies

Diffuse high-grade gliomas contain some of the most dangerous human cancers that lack curative treatment options. The recent molecular stratification of gliomas by the World Health Organisation in 2021 is expected to improve outcomes for patients in neuro-oncology through the development of treatments targeted to specific tumour types. Despite this promise, research is hindered by the lack of preclinical modelling platforms capable of recapitulating the heterogeneity and cellular phenotypes of tumours residing in their native human brain microenvironment. The microenvironment provides cues to subsets of glioma cells that influence proliferation, survival, and gene expression, thus altering susceptibility to therapeutic intervention. As such, conventional in vitro cellular models poorly reflect the varied responses to chemotherapy and radiotherapy seen in these diverse cellular states that differ in transcriptional profile and differentiation status. In an effort to improve the relevance of traditional modelling platforms, recent attention has focused on human pluripotent stem cell-based and tissue engineering techniques, such as three-dimensional (3D) bioprinting and microfluidic devices. The proper application of these exciting new technologies with consideration of tumour heterogeneity and microenvironmental interactions holds potential to develop more applicable models and clinically relevant therapies. In doing so, we will have a better chance of translating preclinical research findings to patient populations, thereby addressing the current derisory oncology clinical trial success rate.

Pluripotent stem cell-derived committed cardiac progenitors remuscularize damaged ischemic hearts and improve their function in pigs

Ischemic heart disease, which is often associated with irreversibly damaged heart muscle, is a major global health burden. Here, we report the potential of stem cell-derived committed cardiac progenitors (CCPs) have in regenerative cardiology. Human pluripotent embryonic stem cells were differentiated to CCPs on a laminin 521 + 221 matrix, characterized with bulk and single-cell RNA sequencing, and transplanted into infarcted pig hearts. CCPs differentiated for eleven days expressed a set of genes showing higher expression than cells differentiated for seven days. Functional heart studies revealed significant improvement in left ventricular ejection fraction at four and twelve weeks following transplantation. We also observed significant improvements in ventricular wall thickness and a reduction in infarction size after CCP transplantation (p-value < 0.05). Immunohistology analyses revealed in vivo maturation of the CCPs into cardiomyocytes (CM). We observed temporary episodes of ventricular tachyarrhythmia (VT) in four pigs and persistent VT in one pig, but the remaining five pigs exhibited normal sinus rhythm. Importantly, all pigs survived without the formation of any tumors or VT-related abnormalities. We conclude that pluripotent stem cell-derived CCPs constitute a promising possibility for myocardial infarction treatment and that they may positively impact regenerative cardiology.

Comparison of two supporting matrices for patient-derived cancer cells in 3D drug sensitivity and resistance testing assay (3D-DSRT)

Central to the success of functional precision medicine of solid tumors is to perform drug testing of patient-derived cancer cells (PDCs) in tumor-mimicking ex vivo conditions. While high throughput (HT) drug screening methods have been well-established for cells cultured in two-dimensional (2D) format, this approach may have limited value in predicting clinical responses. Here, we describe the results of the optimization of drug sensitivity and resistance testing (DSRT) in three-dimensional (3D) growth supporting matrices in a HT mode (3D-DSRT) using the hepatocyte cell line (HepG2) as an example. Supporting matrices included widely used animal-derived Matrigel and cellulose-based hydrogel, GrowDex, which has earlier been shown to support 3D growth of cell lines and stem cells. Further, the sensitivity of ovarian cancer PDCs, from two patients included in the functional precision medicine study, was tested for 52 drugs in 5 different concentrations using 3D-DSRT. Shortly, in the optimized protocol, the PDCs are embedded with matrices and seeded to 384-well plates to allow the formation of the spheroids prior to the addition of drugs in nanoliter volumes with acoustic dispenser. The sensitivity of spheroids to drug treatments is measured with cell viability readout (here, 72 h after addition of drugs). The quality control and data analysis are performed with openly available Breeze software. We show the usability of both matrices in established 3D-DSRT, and report 2D vs 3D growth condition dependent differences in sensitivities of ovarian cancer PDCs to MEK-inhibitors and cytotoxic drugs. This study provides a proof-of-concept for robust and fast screening of drug sensitivities of PDCs in 3D-DSRT, which is important not only for drug discovery but also for personalized ex vivo drug testing in functional precision medicine studies. These findings suggest that comparing results of 2D- and 3D-DSRT is essential for understanding drug mechanisms and for selecting the most effective treatment for the patient.

Current possibilities and future opportunities provided by three-dimensional lung ECM-derived hydrogels

Disruption of the complex interplay between cells and extracellular matrix (ECM), the scaffold that provides support, biochemical and biomechanical cues, is emerging as a key element underlying lung diseases. We readily acknowledge that the lung is a flexible, relatively soft tissue that is three dimensional (3D) in structure, hence a need exists to develop in vitro model systems that reflect these properties. Lung ECM-derived hydrogels have recently emerged as a model system that mimics native lung physiology; they contain most of the plethora of biochemical components in native lung, as well as reflecting the biomechanics of native tissue. Research investigating the contribution of cell:matrix interactions to acute and chronic lung diseases has begun adopting these models but has yet to harness their full potential. This perspective article provides insight about the latest advances in the development, modification, characterization and utilization of lung ECM-derived hydrogels. We highlight some opportunities for expanding research incorporating lung ECM-derived hydrogels and potential improvements for the current approaches. Expanding the capabilities of investigations using lung ECM-derived hydrogels is positioned at a cross roads of disciplines, the path to new and innovative strategies for unravelling disease underlying mechanisms will benefit greatly from interdisciplinary approaches. While challenges need to be addressed before the maximum potential can be unlocked, with the rapid pace at which this field is evolving, we are close to a future where faster, more efficient and safer drug development targeting the disrupted 3D microenvironment is possible using lung ECM-derived hydrogels.

Towards Standardisation of a Diffuse Midline Glioma Patient-Derived Xenograft Mouse Model Based on Suspension Matrices for Preclinical Research

Diffuse midline glioma (DMG) is an aggressive brain tumour with high mortality and limited clinical therapeutic options. Although in vitro research has shown the effectiveness of medication, successful translation to the clinic remains elusive. A literature search highlighted the high variability and lack of standardisation in protocols applied for establishing the commonly used HSJD-DIPG-007 patient-derived xenograft (PDX) model, based on animal host, injection location, number of cells inoculated, volume, and suspension matrices. This study evaluated the HSJD-DIPG-007 PDX model with respect to its ability to mimic human disease progression for therapeutic testing in vivo. The mice received intracranial injections of HSJD-DIPG-007 cells suspended in either PBS or Matrigel. Survival, tumour growth, and metastases were assessed to evaluate differences in the suspension matrix used. After cell implantation, no severe side effects were observed. Additionally, no differences were detected in terms of survival or tumour growth between the two suspension groups. We observed delayed metastases in the Matrigel group, with a significant difference compared to mice with PBS-suspended cells. In conclusion, using Matrigel as a suspension matrix is a reliable method for establishing a DMG PDX mouse model, with delayed metastases formation and is a step forward to obtaining a standardised in vivo PDX model.

Multimodal Techniques to Study Tumor Growth, Basement Membrane Breaching, and Invasion in 3D Matrices

Cancer-derived organoids and three-dimensional (3D) extracellular matrix (ECM) are taking center stage as in vitro models to study neoplastic cell behavior, since they recapitulate the heterogeneous cellular composition of tumors and their extracellular environment. In combination with imaging and molecular/biochemical techniques, 3D organoid models have contributed substantially to our knowledge about the cellular and molecular mechanisms that regulate the growth of tumors and invasion into the surrounding tissue. We here outline a set of protocols that describe culturing of cancer-derived organoids in 3D matrices and various strategies that allow modeling of tumor growth, tumor cell penetration into basement membranes, and invasion into Collagen I-rich ECM. Furthermore, we specify protocols for subsequent handling of organoids cultured in 3D ECM for confocal microscopy and analysis of gene expression at the protein and mRNA level. Although we here use breast cancer-derived organoids, these protocols can be directly applied or adapted for organoids derived from other cancer types or healthy tissues. Thus, in addition to investigating cell behavior of multiple cancer types, the combination of protocols described here may be used to study processes such as cell differentiation and migration during homeostasis and normal development.

Application of sequential cyclic compression on cancer cells in a flexible microdevice

Mechanical forces shape physiological structure and function within cell and tissue microenvironments, during which cells strive to restore their shape or develop an adaptive mechanism to maintain cell integrity depending on strength and type of the mechanical loading. While some cells are shown to experience permanent plastic deformation after a repetitive mechanical tensile loading and unloading, the impact of such repetitive compression on deformation of cells is yet to be understood. As such, the ability to apply cyclic compression is crucial for any experimental setup aimed at the study of mechanical compression taking place in cell and tissue microenvironments. Here, we demonstrate such cyclic compression using a microfluidic compression platform on live cell actin in SKOV-3 ovarian cancer cells. Live imaging of the actin cytoskeleton dynamics of the compressed cells was performed for varying pressures applied sequentially in ascending order during cell compression. Additionally, recovery of the compressed cells was investigated by capturing actin cytoskeleton and nuclei profiles of the cells at zero time and 24 h-recovery after compression in end point assays. This was performed for a range of mild pressures within the physiological range. Results showed that the phenotypical response of compressed cells during recovery after compression with 20.8 kPa differed observably from that for 15.6 kPa. This demonstrated the ability of the platform to aid in the capture of differences in cell behaviour as a result of being compressed at various pressures in physiologically relevant manner. Differences observed between compressed cells fixed at zero time or after 24 h-recovery suggest that SKOV-3 cells exhibit deformations at the time of the compression, a proposed mechanism cells use to prevent mechanical damage. Thus, biomechanical responses of SKOV-3 ovarian cancer cells to sequential cyclic compression and during recovery after compression could be revealed in a flexible microdevice. As demonstrated in this work, the observation of morphological, cytoskeletal and nuclear differences in compressed and non-compressed cells, with controlled micro-scale mechanical cell compression and recovery and using live-cell imaging, fluorescent tagging and end point assays, can give insights into the mechanics of cancer cells.

3D cell culture model: From ground experiment to microgravity study

Microgravity has been shown to induce many changes in cell growth and differentiation due to offloading the gravitational strain normally exerted on cells. Although many studies have used two-dimensional (2D) cell culture systems to investigate the effects of microgravity on cell growth, three-dimensional (3D) culture scaffolds can offer more direct indications of the modified cell response to microgravity-related dysregulations compared to 2D culture methods. Thus, knowledge of 3D cell culture is essential for better understanding the in vivo tissue function and physiological response under microgravity conditions. This review discusses the advances in 2D and 3D cell culture studies, particularly emphasizing the role of hydrogels, which can provide cells with a mimic in vivo environment to collect a more natural response. We also summarized recent studies about cell growth and differentiation under real microgravity or simulated microgravity conditions using ground-based equipment. Finally, we anticipate that hydrogel-based 3D culture models will play an essential role in constructing organoids, discovering the causes of microgravity-dependent molecular and cellular changes, improving space tissue regeneration, and developing innovative therapeutic strategies. Future research into the 3D culture in microgravity conditions could lead to valuable therapeutic applications in health and pharmaceuticals.

Differentiating Human Pluripotent Stem Cells to Cardiomyocytes Using Purified Extracellular Matrix Proteins

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) can be differentiated into cardiomyocytes (hESC-CMs and iPSC-CMs, respectively), which hold great promise for cardiac regenerative medicine and disease modeling efforts. However, the most widely employed differentiation protocols require undefined substrates that are derived from xenogeneic (animal) products, contaminating resultant hESC- and iPSC-CM cultures with xenogeneic proteins and limiting their clinical applicability. Additionally, typical hESC- and iPSC-CM protocols produce CMs that are significantly contaminated by non-CMs and that are immature, requiring lengthy maturation procedures. In this review, we will summarize recent studies that have investigated the ability of purified extracellular matrix (ECM) proteins to support hESC- and iPSC-CM differentiation, with a focus on commercially available ECM proteins and coatings to make such protocols widely available to researchers. The most promising of the substrates reviewed here include laminin-521 with laminin-221 together or Synthemax (a synthetic vitronectin-based peptide coating), which both resulted in highly pure CM cultures. Future efforts are needed to determine whether combinations of specific purified ECM proteins or derived peptides could further improve CM maturation and culture times, and significantly improve hESC- and iPSC-CM differentiation protocols.

Focus on organoids: cooperation and interconnection with extracellular vesicles - Is this the future of in vitro modeling?

Organoids are simplified in vitro model systems of organs that are used for modeling tissue development and disease, drug screening, cell therapy, and personalized medicine. Despite considerable success in the design of organoids, challenges remain in achieving real-life applications. Organoids serve as unique and organized groups of micro physiological systems that are capable of self-renewal and self-organization. Moreover, they exhibit similar organ functionality(ies) as that of tissue(s) of origin. Organoids can be designed from adult stem cells, induced pluripotent stem cells, or embryonic stem cells. They consist of most of the important cell types of the desired tissue/organ along with the topology and cell-cell interactions that are highly similar to those of an in vivo tissue/organ. Organoids have gained interest in human biomedical research, as they demonstrate high promise for use in basic, translational, and applied research. As in vitro models, organoids offer significant opportunities for reducing the reliance and use of experimental animals. In this review, we will provide an overview of organoids, as well as those intercellular communications mediated by extracellular vesicles (EVs), and discuss the importance of organoids in modeling a tumor immune microenvironment (TIME). Organoids can also be exploited to develop a better understanding of intercellular communications mediated by EVs. Also, organoids are useful in mimicking TIME, thereby offering a better-controlled environment for studying various associated biological processes and immune cell types involved in tumor immunity, such as T-cells, macrophages, dendritic cells, and myeloid-derived suppressor cells, among others.

Engineering collagenous analogs of connective tissue extracellular matrix

Connective tissue extracellular matrix (ECM) consists of an interwoven network of contiguous collagen fibers that regulate cell activity, direct biological function, and guide tissue homeostasis throughout life. Recently, ECM analogs have emerged as a unique ex vivo culture platform for studying healthy and diseased tissues and in the latter, enabling the screening for and development of therapeutic regimen. Since these tissue models can mitigate the concern that observations from animal models do not always translate clinically, the design and production of a collagenous ECM analogue with relevant chemistry and nano- to micro-scale architecture remains a frontier challenge in the field. Therefore, the objectives of this study are two-fold— first, to apply green electrospinning approaches to the fabrication of an ECM analog with nanoscale mimicry and second, to systematically optimize collagen crosslinking in order to produce a stable, collagen-like substrate with continuous fibrous architecture that supports human cell culture and phenotypic expression. Specifically, the “green” electrospinning solvent acetic acid was evaluated for biofabrication of gelatin-based meshes, followed by the optimization of glutaraldehyde (GTA) crosslinking under controlled ambient conditions. These efforts led to the production of a collagen-like mesh with nano- and micro-scale cues, fibrous continuity with little batch-to-batch variability, and proven stability in both dry and wet conditions. Moreover, the as-fabricated mesh architecture and native chemistry were preserved with augmented mechanical properties. These meshes supported the in vitro expansion of stem cells and the production of a mineralized matrix by human osteoblast-like cells. Collectively these findings demonstrate the potential of green fabrication in the production of a collagen-like ECM analog with physiological relevance. Future studies will explore the potential of this high-fidelity platform for elucidating cell-matrix interactions and their relevance in connective tissue healing.

Renal oncometabolite L-2-hydroxyglutarate imposes a block in kidney tubulogenesis: Evidence for an epigenetic basis for the L-2HG-induced impairment of differentiation

2-Hydroxyglutarate (2HG) overproducing tumors arise in a number of tissues, including the kidney. The tumorigenesis resulting from overproduced 2HG has been attributed to the ability of 2HG alter gene expression by inhibiting α-ketoglutarate (αKG)-dependent dioxygenases, including Ten-eleven-Translocation (TET) enzymes. Genes that regulate cellular differentiation are reportedly repressed, blocking differentiation of mesenchymal cells into myocytes, and adipocytes. In this report, the expression of the enzyme responsible for L2HG degradation, L-2HG dehydrogenase (L2HGDH), is knocked down, using lentiviral shRNA, as well as siRNA, in primary cultures of normal Renal Proximal Tubule (RPT) cells. The knockdown (KD) results in increased L-2HG levels, decreased demethylation of 5mC in genomic DNA, and increased methylation of H3 Histones. Consequences include reduced tubulogenesis by RPT cells in matrigel, and reduced expression of molecular markers of differentiation, including membrane transporters as well as HNF1α and HNF1β, which regulate their transcription. These results are consistent with the hypothesis that oncometabolite 2HG blocks RPT differentiation by altering the methylation status of chromatin in a manner that impedes the transcriptional events required for normal differentiation. Presumably, similar alterations are responsible for promoting the expansion of renal cancer stem-cells, increasing their propensity for malignant transformation.

Reconstructing the pulmonary niche with stem cells: a lung story

The global burden of pulmonary disease highlights an overwhelming need in improving our understanding of lung development, disease, and treatment. It also calls for further advances in our ability to engineer the pulmonary system at cellular and tissue levels. The discovery of human pluripotent stem cells (hPSCs) offsets the relative inaccessibility of human lungs for studying developmental programs and disease mechanisms, all the while offering a potential source of cells and tissue for regenerative interventions. This review offers a perspective on where the lung stem cell field stands in terms of accomplishing these ambitious goals. We will trace the known stages and pathways involved in in vivo lung development and how they inspire the directed differentiation of stem and progenitor cells in vitro. We will also recap the efforts made to date to recapitulate the lung stem cell niche in vitro via engineered cell–cell and cell-extracellular matrix (ECM) interactions.

In vivo transcriptomic profiling using cell encapsulation identifieseffector pathways of systemic aging

Sustained exposure to a young systemic environment rejuvenates aged organisms and promotes cellular function. However, due to the intrinsic complexity of tissues it remains challenging to pinpoint niche-independent effects of circulating factors on specific cell populations. Here, we describe a method for the encapsulation of human and mouse skeletal muscle progenitors in diffusible polyethersulfone hollow fiber capsules that can be used to profile systemic aging in vivo independent of heterogeneous short-range tissue interactions. We observed that circulating long-range signaling factors in the old systemic environment lead to an activation of Myc and E2F transcription factors, induce senescence, and suppress myogenic differentiation. Importantly, in vitro profiling using young and old serum in 2D culture does not capture all pathways deregulated in encapsulated cells in aged mice. Thus, in vivo transcriptomic profiling using cell encapsulation allows for the characterization of effector pathways of systemic aging with unparalleled accuracy.

Bioinspired Sandcastle Worm-Derived Peptide-Based Hybrid Hydrogel for Promoting the Formation of Liver Spheroids

The generation of hepatic spheroids is beneficial for a variety of potential applications, including drug development, disease modeling, transplantation, and regenerative medicine. Natural hydrogels are obtained from tissues and have been widely used to promote the growth, differentiation, and retention of specific functionalities of hepatocytes. However, relying on natural hydrogels for the generation of hepatic spheroids, which have batch to batch variations, may in turn limit the previously mentioned potential applications. For this reason, we researched a way to establish a three-dimensional (3D) culture system that more closely mimics the interaction between hepatocytes and their surrounding microenvironments, thereby potentially offering a more promising and suitable system for drug development, disease modeling, transplantation, and regenerative medicine. Here, we developed self-assembling and bioactive hybrid hydrogels to support the generation and growth of hepatic spheroids. Our hybrid hydrogels (PC4/Cultrex) inspired by the sandcastle worm, an Arg-Gly-Asp (RGD) cell adhesion sequence, and bioactive molecules derived from Cultrex BME (Basement Membrane Extract). By performing optimizations to the design, the PC4/Cultrex hybrid hydrogels can enhance HepG2 cells to form spheroids and express their molecular signatures (e.g., Cyp3A4, Cyp7a1, A1at, Afp, Ck7, Ck1, and E-cad). Our study demonstrated that this hybrid hydrogel system offers potential advantages for hepatocytes in proliferating, differentiating, and self-organizing to form hepatic spheroids in a more controllable and reproducible manner. In addition, it is a versatile and cost-effective method for 3D tissue cultures in mass quantities. Importantly, we demonstrate that it is feasible to adapt a bioinspired approach to design biomaterials for 3D culture systems, which accelerates the design of novel peptide structures and broadens our research choices on peptide-based hydrogels.

Instructive Hydrogels for Primary Tumor Cell Culture: Current Status and Outlook

Primary tumor organoids (PTOs) growth in hydrogels have emerged as an important in vitro model that recapitulates many characteristics of the native tumor tissue, and have important applications in fundamental cancer research and for the development of useful therapeutic treatment. This paper begins with reviewing the methods of isolation of primary tumor cells. Then, recent advances on the instructive hydrogels as biomimetic extracellular matrix for primary tumor cell culture and construction of PTO models are summarized. Emerging microtechnology for growth of PTOs in microscale hydrogels and the applications of PTOs are highlighted. This paper concludes with an outlook on the future directions in the investigation of instructive hydrogels for PTO growth.

Modeling Early Neural Crest Development via Induction from hiPSC-Derived Neural Plate Border-like Cells

Neural crest cells (NCCs) are a multipotent and transient cell population that gives rise to many important tissues during human embryogenesis. Disturbances that occur during NCCs development may lead to numerous types of diseases and syndromes, which are called neurocristopathies. NCCs in vitro modeling enables the access to cellular, genetic, and biochemical information about the neural crest development and its derivatives. By using cells derived from patients with neurocristopathies it is possible to study the cellular and genetic mechanisms behind each disease in a specific and trustworthy manner, as well as to contribute to the development of prospective treatments. Here, we describe a protocol of 19 days, capable of efficiently generating NCCs from human induced pluripotent stem cells (hiPSCs). This differentiation process recapitulates the intermediate stage of neural plate border-like cells (NBCs), the epithelial to mesenchymal transition (EMT), and enables further generation of NCCs derivatives, such as Schwann cells, smooth muscle cells, melanocytes, peripheral neurons, adipocytes, osteoblasts, and chondrocytes.

Physical and chemical properties of carbon nanotubes in view of mechanistic neuroscience investigations. Some outlook from condensed matter, materials science and physical chemistry

The open border between non-living and living matter, suggested by increasingly emerging fields of nanoscience interfaced to biological systems, requires a detailed knowledge of nanomaterials properties. An account of the wide spectrum of phenomena, belonging to physical chemistry of interfaces, materials science, solid state physics at the nanoscale and bioelectrochemistry, thus is acquainted for a comprehensive application of carbon nanotubes interphased with neuron cells. This review points out a number of conceptual tools to further address the ongoing advances in coupling neuronal networks with (carbon) nanotube meshworks, and to deepen the basic issues that govern a biological cell or tissue interacting with a nanomaterial. Emphasis is given here to the properties and roles of carbon nanotube systems at relevant spatiotemporal scales of individual molecules, junctions and molecular layers, as well as to the point of view of a condensed matter or materials scientist. Carbon nanotube interactions with blood-brain barrier, drug delivery, biocompatibility and functionalization issues are also regarded.

Bioengineering Approaches for the Advanced Organoid Research

Recent advances in 3D cell culture technology have enabled scientists to generate stem cell derived organoids that recapitulate the structural and functional characteristics of native organs. Current organoid technologies have been striding toward identifying the essential factors for controlling the processes involved in organoid development, including physical cues and biochemical signaling. There is a growing demand for engineering dynamic niches characterized by conditions that resemble in vivo organogenesis to generate reproducible and reliable organoids for various applications. Innovative biomaterial-based and advanced engineering-based approaches have been incorporated into conventional organoid culture methods to facilitate the development of organoid research. The recent advances in organoid engineering, including extracellular matrices and genetic modulation, are comprehensively summarized to pinpoint the parameters critical for organ-specific patterning. Moreover, perspective trends in developing tunable organoids in response to exogenous and endogenous cues are discussed for next-generation developmental studies, disease modeling, and therapeutics.

Novel Human Placenta-Based Extract for Vascularization Strategies in Tissue Engineering

There is critical unmet need for new vascularized tissues to support or replace injured tissues and organs. Various synthetic and natural materials were already established for use of two-dimensional (2D) and three-dimensional (3D) in vitro neovascularization assays, however, they still cannot mimic the complex functions of the sum of the extracellular matrix (ECM) in native intact tissue. Currently, this issue is only addressed by artificial products such as Matrigel^™, which comprises a complex mixture of ECM proteins, extracted from animal tumor tissue. Despite its outstanding bioactivity, the isolation from tumor tissue hinders its translation into clinical applications. Since nonhuman ECM proteins may cause immune reactions, as are frequently observed in clinical trials, human ECM proteins represent the best option when aiming for clinical applications. Here, we describe an effective method of isolating a human placenta substrate (hpS) that induces the spontaneous formation of an interconnected network of green fluorescence-labeled human umbilical vein endothelial cells (gfpHUVECs) in vitro. The substrate was biochemically characterized by using a combination of bicinchoninic acid (BCA) assay, DNA, and glycosaminoglycan (GAG) content assays, sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) analysis and Western blot, angiogenesis arrays, chromatographic thrombin detection, high performance liquid chromatography (HPLC)-based amino acid quantification analysis, and assessment of antimicrobial properties. 2D in vitro cell culture experiments have been performed to determine the vasculogenic potential of hpS, which demonstrated that cell networks developed on hpS show a significantly higher degree of complexity (number of tubules/junctions; total/mean tube length) when compared with Matrigel. As 3D cell culture techniques represent a more accurate representation of the in vivo condition, the substrate was 3D solidified using various natural polymers. 3D in vitro vasculogenesis assays have been performed by seeding gfpHUVECs in an hpS-fibrinogen clot. In conclusion, hpS provides a potent human/material-based alternative to xenogenic-material-based biomaterials for vascularization strategies in tissue engineering.

Germline CDH1 G212E Missense Variant: Combining Clinical, In Vitro and In Vivo Strategies to Unravel Disease Burden

Simple Summary

Hereditary diffuse gastric cancer (HDGC) is an inherited cancer syndrome associated with CDH1 germline mutations. The increasing detection of CDH1 genetic variants due to multigene panel testing poses a serious clinical challenge and urges the development of effective classification strategies. In this study, we describe the identification of the novel CDH1 G212E variant in a large family strongly affected by diffuse gastric cancer. Through a comprehensive characterization pipeline, we provide evidence of the damaging nature of this genetic alteration, thus impacting patient management and family screening.

Abstract

E-cadherin, encoded by CDH1, is an essential molecule for epithelial homeostasis, whose loss or aberrant expression results in disturbed cell–cell adhesion, increased cell invasion and metastasis. Carriers of CDH1 germline mutations have a high risk of developing diffuse gastric cancer and lobular breast cancer, associated with the cancer syndrome Hereditary Diffuse Gastric Cancer (HDGC). The ubiquitous availability of cancer panels has led to the identification of an increasing amount of “incidental” CDH1 genetic variants that pose a serious clinical challenge. This has sparked intensive research aiming at an accurate classification of the variants and consequent validation of their clinical relevance. The present study addressed the significance of a novel CDH1 variant, G212E, identified in an unusually large pedigree displaying strong aggregation of diffuse gastric cancer. We undertook a comprehensive pipeline encompassing family data, in silico predictions, in vitro assays and in vivo strategies, which validated the deleterious phenotype induced by this genetic alteration. In particular, we demonstrated that the G212E variant affects the stability and localization, as well as the adhesive and anti-invasive functions of E-cadherin, triggering epithelial disruption and disorganization. Our findings illustrate the clinical implication of a complementary approach for effective variant categorization and patient management.

Sequence-dependent mechanics of collagen reflect its structural and functional organization

Extracellular matrix mechanics influence diverse cellular functions, yet surprisingly little is known about the mechanical properties of their constituent collagen proteins. In particular, network-forming collagen IV, an integral component of basement membranes, has been far less studied than fibril-forming collagens. A key feature of collagen IV is the presence of interruptions in the triple-helix-defining (Gly-X-Y) sequence along its collagenous domain. Here, we used atomic force microscopy to determine the impact of sequence heterogeneity on the local flexibility of collagen IV and of the fibril-forming collagen III. Our extracted flexibility profile of collagen IV reveals that it possesses highly heterogeneous mechanics, ranging from semiflexible regions as found for fibril-forming collagens to a lengthy region of high flexibility toward its N-terminus. A simple model in which flexibility is dictated only by the presence of interruptions fit the extracted profile reasonably well, providing insight into the alignment of chains and demonstrating that interruptions, particularly when coinciding in multiple chains, significantly enhance local flexibility. To a lesser extent, sequence variations within the triple helix lead to variable flexibility, as seen along the continuously triple-helical collagen III. We found this fibril-forming collagen to possess a high-flexibility region around its matrix-metalloprotease binding site, suggesting a unique mechanical fingerprint of this region that is key for matrix remodeling. Surprisingly, proline content did not correlate with local flexibility in either collagen type. We also found that physiologically relevant changes in pH and chloride concentration did not alter the flexibility of collagen IV, indicating such environmental changes are unlikely to control its compaction during secretion. Although extracellular chloride ions play a role in triggering collagen IV network formation, they do not appear to modulate the structure of its collagenous domain.

Simplification of culture conditions and feeder-free expansion of bovine embryonic stem cells

Bovine embryonic stem cells (bESCs) extend the lifespan of the transient pluripotent bovine inner cell mass in vitro. After years of research, derivation of stable bESCs was only recently reported. Although successful, bESC culture relies on complex culture conditions that require a custom-made base medium and mouse embryonic fibroblasts (MEF) feeders, limiting the widespread use of bESCs. We report here simplified bESC culture conditions based on replacing custom base medium with a commercially available alternative and eliminating the need for MEF feeders by using a chemically-defined substrate. bESC lines were cultured and derived using a base medium consisting of N2B27 supplements and 1% BSA (NBFR-bESCs). Newly derived bESC lines were easy to establish, simple to propagate and stable after long-term culture. These cells expressed pluripotency markers and actively proliferated for more than 35 passages while maintaining normal karyotype and the ability to differentiate into derivatives of all three germ lineages in embryoid bodies and teratomas. In addition, NBFR-bESCs grew for multiple passages in a feeder-free culture system based on vitronectin and Activin A medium supplementation while maintaining pluripotency. Simplified conditions will facilitate the use of bESCs for gene editing applications and pluripotency and lineage commitment studies.

Extracellular Matrix Components Regulate Bone Sialoprotein Expression in MDA-MB-231 Breast Cancer Cells

Bone sialoprotein (BSP) has become a target in breast cancer research as it is associated with tumor progression and metastasis. The mechanisms underlying the regulation of BSP expression have been largely elusive. Given that BSP is involved in the homing of cancer cells in bone metastatic niches, we addressed regulatory effects of proteolytic cleavage and extracellular matrix components on BSP expression and distribution in cell culture models. Therefore, MDA-MB-231 human breast cancer cells were kept in 2D and 3D spheroid cultures and exposed to basement membrane extract in the presence or absence of matrix metalloproteinase 9 or the non-polar protease, dispase. Confocal imaging of immunofluorescence samples stained with different antibodies against human BSP demonstrated a strong inducing effect of basement membrane extract on anti-BSP immunofluorescence. Similarly, protease incubation led to acute upregulation of anti-BSP immunofluorescence signals, which was blocked by cycloheximide, suggesting de novo formation of BSP. In summary, our data show that extracellular matrix components play an important function in regulating BSP expression and hint at mechanisms for the formation of bone-associated metastasis in breast cancer that might involve local control of BSP levels by extracellular matrix degradation and release of growth factors.

Tumor Extrinsic Factors Mediate Primary T-DM1 Resistance in HER2-Positive Breast Cancer Cells

Simple Summary

In this investigation, we employed an unconventional approach to explore the mechanisms of the primary resistance of human epidermal growth factor 2 (HER2)-positive breast cancer cells to ado-trastuzumab emtansine (also known as T-DM1). Specifically, we used Matrigel matrix as a model of the tumor microenvironment and examined its effect on the sensitivity of HER2-positive breast cancer cells to T-DM1. We found that epidermal growth factor receptor (EGFR) is activated in HER2-positive, T-DM1-sensitive JIMT1 and SKBR-3 cells on the Matrigel matrix. This leads to phosphorylation and degradation of HER2 in these cells, resulting in the loss of or reduced sensitivity to T-DM1. The discovery of extrinsic factors contributing to the primary resistance of HER2-positive breast cancer cells to T-DM1 provides an opportunity to develop a novel therapeutic strategy to overcome T-DM1 resistance.

Abstract

To explore if the tumor microenvironment contributes to the primary resistance of HER2-positive breast cancer cells to T-DM1, we examined whether Matrigel, a basement membrane matrix that provides a three-dimensional (3D) cell culture condition, caused the primary resistance of HER2-positive, T-DM1-sensitive breast cancer cells (JIMT1 and SKBR-3 cells) to T-DM1. This is different from the conventional approach such that the cells are exposed with escalated doses of drug to establish a drug-resistant cell line. We found that these cells were able to grow and form spheroids on the Matrigel in the presence of T-DM1. We further explored the molecular mechanisms that enables these cells to be primarily resistant to T-DM1 and found that EGFR was activated in the spheroids, leading to an increased HER2 tyrosine phosphorylation. This in turn enhances cell growth signaling downstream of EGFR/HER2 in the spheroids. HER2 tyrosine phosphorylation promotes receptor internalization and degradation in the spheroids, which limits T-DM1 access to HER2 on the cell surface of spheroids. Blocking EGFR activity by erlotinib reduces HER2 tyrosine phosphorylation and enhances HER2 cell surface expression. This enables T-DM1 to gain access to HER2 on the cell surface, resumes cell sensitivity to T-DM1, and exhibits synergistic activity with T-DM1 to inhibit the formation of spheroids on Matrigel. The discovery described in this manuscript reveals a novel approach to investigate the primary resistance of HER2-positive breast cancer cells and provides an opportunity to develop a therapeutic strategy to overcome primary resistance to T-DM1 by combing T-DM1 therapy with kinase inhibitors of EGFR.

Suppression of TGF-β1 signaling by Matrigel via FAK signaling in cultured human trabecular meshwork cells

The trabecular meshwork (TM) is composed of TM cells and beams of the extracellular matrix, together contributing to aqueous humor (AH) outflow resistance. Herein, we validated that our culture system on 2D Matrigel expressed putative TM markers and myocilin, of which the latter was upregulated by dexamethasone. Continuous passage of these cells on 2D Matrigel resulted in a gradual loss of expression of these markers. However, such a loss was restored by seeding cells in 3D Matrigel where expression of TM markers was further upregulated upon continuous passage. In contrast, TM cells seeded on fibronectin, collagen I/IV, or laminin lost expression of these markers and turned into myofibroblasts with expression of αSMA, which were dose-dependently upregulated by TGF-β1/TGF-β2. TM cells in 3D Matrigel also expressed TGF-β1/TGF-β3 despite challenge of TGF-β1. The maintenance of TM phenotype by 3D Matrigel was linked to inhibition of canonical TGF-β signaling and activation of pFAK-pSrc-pP190RhoGAP-P120RasGAP signaling. These findings indicate that basement membrane matrix with low rigidity plays an active role in maintaining TM phenotype in the presence of TGF-β1 and shed light on its physiological role. Furthermore, abnormal matrices may perpetuate the pathological TM phenotype when the level of TGF-β2 is elevated in glaucoma patients.

Organoid Technology: Current Standing and Future Perspectives

Organoids are powerful systems to facilitate the study of individuals' disorders and personalized treatments. Likewise, emerging this technology has improved the chance of translatability of drugs for pre-clinical therapies and mimicking the complexity of organs, while it proposes numerous approaches for human disease modeling, tissue engineering, drug development, diagnosis, and regenerative medicine. In this review, we outline the past/present organoid technology and summarize its faithful applications, then, we discuss the challenges and limitations encountered by 3D organoids. In the end, we offer the human organoids as basic mechanistic infrastructure for "human modelling" systems to prescribe personalized medicines. © AlphaMed Press 2021 SIGNIFICANCE STATEMENT: This concise review concerns about organoids, available methods for in vitro organoid formation and different types of human organoid models. We, then, summarize biological approaches to improve 3D organoids complexity and therapeutic potentials of organoids. Despite the existing incomprehensive review articles in literature that examine partial aspects of the organoid technology, the present review article comprehensively and critically presents this technology from different aspects. It effectively provides a systematic overview on the past and current applications of organoids and discusses the future perspectives and suggestions to improve this technology and its applications.

The internal limiting membrane: Roles in retinal development and implications for emerging ocular therapies

Basement membranes help to establish, maintain, and separate their associated tissues. They also provide growth and signaling substrates for nearby resident cells. The internal limiting membrane (ILM) is the basement membrane at the ocular vitreoretinal interface. While the ILM is essential for normal retinal development, it is dispensable in adulthood. Moreover, the ILM may constitute a significant barrier to emerging ocular therapeutics, such as viral gene therapy or stem cell transplantation. Here we take a neurodevelopmental perspective in examining how retinal neurons, glia, and vasculature interact with individual extracellular matrix constituents at the ILM. In addition, we review evidence that the ILM may impede novel ocular therapies and discuss approaches for achieving retinal parenchymal targeting of gene vectors and cell transplants delivered into the vitreous cavity by manipulating interactions with the ILM.

Breast Cancer Reconstruction: Design Criteria for a Humanized Microphysiological System

International regulatory agencies such as the Food and Drug Administration have mandated that the scientific community develop humanized microphysiological systems (MPS) as an in vitro alternative to animal models in the near future. While the breast cancer research community has long appreciated the importance of three-dimensional growth dynamics in their experimental models, there are remaining obstacles preventing a full conversion to humanized MPS for drug discovery and pathophysiological studies. This perspective evaluates the current status of human tissue-derived cells and scaffolds as building blocks for an "idealized" breast cancer MPS based on bioengineering design principles. It considers the utility of adipose tissue as a potential source of endothelial, lymphohematopoietic, and stromal cells for the support of breast cancer epithelial cells. The relative merits of potential MPS scaffolds derived from adipose tissue, blood components, and synthetic biomaterials is evaluated relative to the current "gold standard" material, Matrigel, a murine chondrosarcoma-derived basement membrane-enriched hydrogel. The advantages and limitations of a humanized breast cancer MPS are discussed in the context of in-process and destructive read-out assays. Impact statement Regulatory authorities have highlighted microphysiological systems as an emerging tool in breast cancer research. This has been led by calls for more predictive human models and reduced animal experimentation. This perspective describes how human-derived cells, extracellular matrices, and hydrogels will provide the building blocks to create breast cancer models that accurately reflect diversity at multiple levels, that is, patient ethnicity, pathophysiology, and metabolic status.

A Natural Xenogeneic Endometrial Extracellular Matrix Hydrogel Toward Improving Current Human in vitro Models and Future in vivo Applications

Decellularization techniques support the creation of biocompatible extracellular matrix hydrogels, providing tissue-specific environments for both in vitro cell culture and in vivo tissue regeneration. We obtained endometrium derived from porcine decellularized uteri to create endometrial extracellular matrix (EndoECM) hydrogels. After decellularization and detergent removal, we investigated the physicochemical features of the EndoECM, including gelation kinetics, ultrastructure, and proteomic profile. The matrisome showed conservation of structural and tissue-specific components with low amounts of immunoreactive molecules. EndoECM supported in vitro culture of human endometrial cells in two- and three-dimensional conditions and improved proliferation of endometrial stem cells with respect to collagen and Matrigel. Further, we developed a three-dimensional endometrium-like co-culture system of epithelial and stromal cells from different origins. Endometrial co-cultures remained viable and showed significant remodeling. Finally, EndoECM was injected subcutaneously in immunocompetent mice in a preliminary study to test a possible hypoimmunogenic reaction. Biomimetic endometrial milieus offer new strategies in reproductive techniques and endometrial repair and our findings demonstrate that EndoECM has potential for in vitro endometrial culture and as treatment for endometrial pathologies.

Current progress, challenges, and future prospects of testis organoids†

Spermatogenic failure is believed to be a major cause of male infertility. The establishment of a testis organoid model would facilitate the study of such pathological mechanisms and open the possibility of male fertility preservation. Because of the complex structures and cellular events occurring within the testis, the establishment of a compartmentalized testis organoid with a complete spermatogenic cycle remains a challenge in all species. Since the late 20th century, a great variety of scaffold-based and scaffold-free testis cell culture systems have been established to recapitulate de novo testis organogenesis and in vitro spermatogenesis. The utilization of the hydrogel scaffolds provides a 3D microenvironment for testis cell growth and development, facilitating the reconstruction of de novo testis tissue-like structures and spermatogenic differentiation. Using a combination of different strategies, including the use of various scaffolding biomaterials, the incorporation of the living cells with high self-assembling capacity, and the integration of the advanced fabrication techniques, a scaffold-based testis organoid with a compartmentalized structure that supports in vitro spermatogenesis may be achieved. This article briefly reviews the current progress in the development of scaffold-based testis organoids while focusing on the scaffolding biomaterials (hydrogels), cell sources, and scaffolding approaches. Key challenges in current organoid studies are also discussed along with recommendations for future research.

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.

Adhesion of anaerobic periodontal pathogens to extracellular matrix proteins

Extracellular matrix (ECM) proteins are highly abundant in the human body and can be found in various tissues, most prominently in connective tissue and basement membrane. For invasive bacterial pathogens, these structures function as physical barriers that block access to underlying tissues. The ability to bind and degrade these barriers is important for the establishment of infections and migration to other body sites. In the oral cavity, the ECM and the basement membrane (BM) are important components of the Junctional epithelium (JE) that closes the gap between the teeth surface and the mucosa. In periodontitis, the JE is breached by invading pathogenic bacteria, particularly strict anaerobic species. In periodontitis, invading microorganisms induce an unregulated and destructive host response through polymicrobial synergism and dysbiosis that attracts immune cells and contributes to the destruction of connective tissue and bone in the periodontal pocket. Colonization of the periodontal pocket is the first step to establish this infection, and binding to ECM is a major advantage in this site. Several species of strict anaerobic bacteria are implicated in acute and chronic periodontitis, and although binding to ECM proteins was studied in these species, few adhesins were identified so far, and the mechanisms involved in adhesion are largely unidentified. This review summarizes the data available on the interaction of strict anaerobic bacteria and components of the ECM.

Review of Integrin-Targeting Biomaterials in Tissue Engineering

The ability to direct cell behavior has been central to the success of numerous therapeutics to regenerate tissue or facilitate device integration. Biomaterial scientists are challenged to understand and modulate the interactions of biomaterials with biological systems in order to achieve effective tissue repair. One key area of research investigates the use of extracellular matrix-derived ligands to target specific integrin interactions and induce cellular responses, such as increased cell migration, proliferation, and differentiation of mesenchymal stem cells. These integrin-targeting proteins and peptides have been implemented in a variety of different polymeric scaffolds and devices to enhance tissue regeneration and integration. This review first presents an overview of integrin-mediated cellular processes that have been identified in angiogenesis, wound healing, and bone regeneration. Then, research utilizing biomaterials are highlighted with integrin-targeting motifs as a means to direct these cellular processes to enhance tissue regeneration. In addition to providing improved materials for tissue repair and device integration, these innovative biomaterials provide new tools to probe the complex processes of tissue remodeling in order to enhance the rational design of biomaterial scaffolds and guide tissue regeneration strategies.

Advanced Materials to Enhance Central Nervous System Tissue Modeling and Cell Therapy

The progressively deeper understanding of mechanisms underlying stem cell fate decisions has enabled parallel advances in basic biology-such as the generation of organoid models that can further one's basic understanding of human development and disease-and in clinical translation-including stem cell based therapies to treat human disease. Both of these applications rely on tight control of the stem cell microenvironment to properly modulate cell fate, and materials that can be engineered to interface with cells in a controlled and tunable manner have therefore emerged as valuable tools for guiding stem cell growth and differentiation. With a focus on the central nervous system (CNS), a broad range of material solutions that have been engineered to overcome various hurdles in constructing advanced organoid models and developing effective stem cell therapeutics is reviewed. Finally, regulatory aspects of combined material-cell approaches for CNS therapies are considered.

Hyaluronate supports hESC-cardiomyocyte cell therapy for cardiac regeneration after acute myocardial infarction

Introduction

Enormous progress has been made in cardiac regeneration using human embryonic stem cell‐derived cardiomyocyte (hESC‐CM) grafts in pre‐clinical trials. However, the rate of cell survival has remained very low due to anoikis after transplantation into the heart as single cells. Numerous solutions have been proposed to improve cell survival, and one of these strategies is to co‐transplant biocompatible materials or hydrogels with the hESC‐CMs.

Methods

In our study, we screened various combinations of biomaterials that could promote anoikis resistance and improve hESC‐CM survival upon co‐transplantation and promote cardiac functional recovery. We injected different combinations of Matrigel, alginate and hyaluronate with hESC‐CM suspensions into the myocardium of rat models with myocardial infarction (MI).

Results

Our results showed that the group treated with a combination of hyaluronate and hESC‐CMs had the lowest arrhythmia rates when stimulated with programmed electrical stimulation. While all three combinations of hydrogel‐hESC‐CM treatments improved rat cardiac function compared with the saline control group, the combination with hyaluronate most significantly reduced pathological changes from left ventricular remodelling and improved both left ventricular function and left ventricular ejection fraction by 28 days post‐infarction.

Conclusion

Hence, we concluded that hyaluronate‐hESC‐CM is a superior combination therapy for promoting cardiac regeneration after myocardial infarction.

Predominant differentiation of rat fetal neural stem cells into functional oligodendrocytes in vitro

Oligodendrocytes form myelin in the CNS. A fast method to produce large quantity of oligodendrocytes that have the capacity of myelinating CNS neurons would be very useful for treating CNS injuries or demyelinating diseases, or for research purposes. We developed a simple standard protocol for predominant differentiation of rat fetal neural stem cells (NSCs) into oligodendrocytes. We adopted a new method to purify the oligodendrocytes and co-cultured the newly differentiated oligodendrocytes with hippocampal neurons to confirm their myelination capability. NSCs from embryonic day 14 (E14) were propagated at the presence of basic fibroblast growth factor and platelet derived growth factor alpha, and then differentiated in the medium containing triiodothyronine. Four extracellular matrix (ECM), poly-d-lysine (PDL), PDL-laminin, fibronectin, and matrigel, were examined for NSC differentiation. About 90 % of NSCs differentiated into oligodendrocytes on matrigel compared to 32 % on PDL or PDL-laminin, and 26 % on fibronectin after 3 weeks of differentiation, demonstrating the significant influence of ECM. Further, newly differentiated oligodendrocytes were co-cultured with hippocampal neurons from E18 rat embryos resulting in robust myelination of neurites at three weeks. In summary, we present a simplified and efficient method to predominantly generate oligodendrocytes from NSCs that is potentially very useful for CNS demyelination diseases.

Hereditary Gastric and Breast Cancer Syndromes Related to CDH1 Germline Mutation: A Multidisciplinary Clinical Review

E-cadherin (CDH1 gene) germline mutations are associated with the development of diffuse gastric cancer in the context of the so-called hereditary diffuse gastric syndrome, and with an inherited predisposition of lobular breast carcinoma. In 2019, the international gastric cancer linkage consortium revised the clinical criteria and established guidelines for the genetic screening of CDH1 germline syndromes. Nevertheless, the introduction of multigene panel testing in clinical practice has led to an increased identification of E-cadherin mutations in individuals without a positive family history of gastric or breast cancers. This observation motivated us to review and present a novel multidisciplinary clinical approach (nutritional, surgical, and image screening) for single subjects who present germline CDH1 mutations but do not fulfil the classic clinical criteria, namely those identified as-(1) incidental finding and (2) individuals with lobular breast cancer without family history of gastric cancer (GC).

Effects of Different Biomaterials and Cellular Status on Testicular Cell Self-Organization

A multicellular organism's development is coupled with cellular self-organization, which is regulated by cell-cell interactions and cell-extracellular matrix (ECM) crosstalk. Testicular cells from different species such as mouse, rat, and porcine can self-organize into seminiferous tubules both in vitro and in vivo, but the understanding of the functional role of the ECM during this process is limited. Here, it is shown that mouse testicular cells encapsulated with the biomaterial Matrigel can self-organize into seminiferous tubules with blood-testis barrier (BTB) formation and Leydig cell differentiation. By varying the encapsulation method, a combination of sodium alginate and collagen is used to promote reorganization of seminiferous tubules, which resemble those in vivo. In addition, the self-organization ability of testicular cells declines with advanced cell age, and those germ cells play a pivotal role in this process. These findings will be helpful to understand the self-organization process of testicular cells and provide insights for the reconstruction of testes.

In Vivo Generation of Post-infarct Human Cardiac Muscle by Laminin-Promoted Cardiovascular Progenitors

Regeneration of injured human heart muscle is limited and an unmet clinical need. There are no methods for the reproducible generation of clinical-quality stem cell-derived cardiovascular progenitors (CVPs). We identified laminin-221 (LN-221) as the most likely expressed cardiac laminin. We produced it as human recombinant protein and showed that LN-221 promotes differentiation of pluripotent human embryonic stem cells (hESCs) toward cardiomyocyte lineage and downregulates pluripotency and teratoma-associated genes. We developed a chemically defined, xeno-free laminin-based differentiation protocol to generate CVPs. We show high reproducibility of the differentiation protocol using time-course bulk RNA sequencing developed from different hESC lines. Single-cell RNA sequencing of CVPs derived from hESC lines supported reproducibility and identified three main progenitor subpopulations. These CVPs were transplanted into myocardial infarction mice, where heart function was measured by echocardiogram and human heart muscle bundle formation was identified histologically. This method may provide clinical-quality cells for use in regenerative cardiology.