An Overview of Cancer Biology, Pathophysiological Development and It's Treatment Modalities: Current Challenges of Cancer anti-Angiogenic Therapy

A number of conditions and factors can cause the transformation of normal cells in the body into malignant tissue by changing the normal functions of a wide range of regulatory, apoptotic, and signal transduction pathways. Despite the current deficiency in fully understanding the mechanism of cancer action accurately and clearly, numerous genes and proteins that are causally involved in the initiation, progression, and metastasis of cancer have been identified. But due to the lack of space and the abundance of details on this complex topic, we have emphasized here more recent advances in our understanding of the principles implied tumor cell transformation, development, invasion, angiogenesis, and metastasis. Inhibition of angiogenesis is a significant strategy for the treatment of various solid tumors, that essentially depend on cutting or at least limiting the supply of blood to micro-regions of tumors, leading to pan-hypoxia and pan-necrosis inside solid tumor tissues. Researchers have continued to enhance the efficiency of anti-angiogenic drugs over the past two decades, to identify their potential in the drug interaction, and to discover reasonable interpretations for possible resistance to treatment. In this review, we have discussed an overview of cancer history and recent methods use in cancer therapy, focusing on anti-angiogenic inhibitors targeting angiogenesis formation. Further, this review has explained the molecular mechanism of action of these anti-angiogenic inhibitors in various tumor types and their limitations use. In addition, we described the synergistic mechanisms of immunotherapy and anti-angiogenic therapy and summarizes current clinical trials of these combinations. Many phase III trials found that combining immunotherapy and anti-angiogenic therapy improved survival. Therefore, targeting the source supply of cancer cells to grow and spread with new anti-angiogenic agents in combination with different conventional therapy is a novel method to reduce cancer progression. The aim of this paper is to overview the varying concepts of cancer focusing on mechanisms involved in tumor angiogenesis and provide an overview of the recent trends in anti-angiogenic strategies for cancer therapy.

Microfluidics single-cell encapsulation reveals that poly-l-lysine-mediated stem cell adhesion to alginate microgels is crucial for cell-cell crosstalk and its self-renewal

Microfluidic cell encapsulation has provided a platform for studying the behavior of individual cells and has become a turning point in single-cell analysis during the last decade. The engineered microenvironment, along with protecting the immune response, has led to increasingly presenting the results of practical and pre-clinical studies with the goals of disease treatment, tissue engineering, intelligent control of stem cell differentiation, and regenerative medicine. However, the significance of cell-substrate interaction versus cell-cell communications in the microgel is still unclear. In this study, monodisperse alginate microgels were generated using a flow-focusing microfluidic device to determine how the cell microenvironment can control human bone marrow-derived mesenchymal stem cells (hBMSCs) viability, proliferation, and biomechanical features in single-cell droplets versus multi-cell droplets. Collected results show insufficient cell proliferation (234 % and 329 %) in both single- and multi-cell alginate microgels. Alginate hydrogels supplemented with poly-l-lysine (PLL) showed a better proliferation rate (514 % and 780 %) in a comparison of free alginate hydrogels. Cell stiffness data illustrate that hBMSCs cultured in alginate hydrogels have higher membrane flexibility and migration potency (Young's modulus equal to 1.06 kPa), whereas PLL introduces more binding sites for cell attachment and causes lower flexibility and migration potency (Young's modulus equal to 1.83 kPa). Considering that cell adhesion is the most important parameter in tissue engineering, in which cells do not run away from a 3D substrate, PLL enhances cell stiffness and guarantees cell attachments. In conclusion, cell attachment to PLL-mediated alginate hydrogels is crucial for cell viability and proliferation. It suggests that cell-cell signaling is good enough for stem cell viability, but cell-PLL attachment alongside cell-cell signaling is crucial for stem cell proliferation and self-renewal.

Avastin-Loaded 3D-Printed Alginate Scaffold as an Effective Antiadhesive Barrier to Prevent Postsurgical Adhesion Bands Formation

Postoperative adhesion can cause complications, such as pain and organ blockage, in the abdominal regions. To address this issue, surgical techniques and antiadhesive treatments are applied. Given the significant role of vascularization in adhesion band formation, Avastin (Ava) that targets vascular endothelial growth factor (VEGF) can be applied to prevent peritoneal adhesion bands. Moreover, Alginate (Alg), a natural polysaccharide, is a promising physical barrier to prevent adhesion bands. Incorporating Ava into Alg hydrogel in a form of 3D-printed scaffold (Alg/Ava) has potential to suppress inflammation and angiogenesis, leading to reduce peritoneal adhesion bands. Following physical, morphological, and biocompatibility evaluations, the efficacy of Alg and Ava alone and their combination in Alg/Ava on the formation of postsurgical adhesions is evaluated. Upon confirming physical stability and sustained release of Ava, the Alg/Ava scaffold effectively diminishes both the extent and strength of adhesion bands. Histopathological examination shows that the reduction in fibrosis and inflammation is responsible for preventing adhesion bands by the Alg/Ava scaffold. Additionally, the cytokine assessment reveals that this is due to the inhibition in the secretion of VEGF and Interleukin 6 suppressing vascularization and inflammatory pathways. This study suggests that a 3D-printed Alg/Ava scaffold has great potential to prevent the postsurgical adhesion bands.

Betulin Stimulates Osteogenic Differentiation of Human Osteoblasts-Loaded Alginate-Gelatin Microbeads

Osteoporosis, a terminal illness, has emerged as a global public health problem in recent years. The long-term use of bone anabolic drugs to treat osteoporosis causes multi-morbidity in elderly patients. Alternative therapies, such as allogenic and autogenic tissue grafts, face important issues, such as a limited source of allogenic grafts and tissue rejection in autogenic grafts. However, stem cell therapy has been shown to increase bone regeneration and decrease osteoporotic bone formation. Stem cell therapy combined with betulin (BET) supplementation might be adequate for bone remodeling and new bone tissue generation. In this study, the effect of BET on the viability and osteogenic differentiation of hFOB 1.19 cells was investigated. The cells were encapsulated in alginate-gelatin (AlGel) microbeads. In vitro tests were conducted during the 12 d of incubation. While BET showed cytotoxic activity (>1 µM) toward non-encapsulated hFOB 1.19 cells, encapsulated cells retained their functionality for up to 12 days, even at 5 µM BET. Moreover, the expression of osteogenic markers indicates an enhanced osteo-inductive effect of betulin on encapsulated hFOB 1.19, compared to the non-encapsulated cell culture. The 3D micro-environment of the AlGel microcapsules successfully protects the hFOB 1.19 cells against BET cytotoxicity, allowing BET to improve the mineralization and differentiation of osteoblast cells.

Biofabrication of engineered blood vessels for biomedical applications

To successfully engineer large-sized tissues, establishing vascular structures is essential for providing oxygen, nutrients, growth factors and cells to prevent necrosis at the core of the tissue. The diameter scale of the biofabricated vasculatures should range from 100 to 1,000 µm to support the mm-size tissue while being controllably aligned and spaced within the diffusion limit of oxygen. In this review, insights regarding biofabrication considerations and techniques for engineered blood vessels will be presented. Initially, polymers of natural and synthetic origins can be selected, modified, and combined with each other to support maturation of vascular tissue while also being biocompatible. After they are shaped into scaffold structures by different fabrication techniques, surface properties such as physical topography, stiffness, and surface chemistry play a major role in the endothelialization process after transplantation. Furthermore, biological cues such as growth factors (GFs) and endothelial cells (ECs) can be incorporated into the fabricated structures. As variously reported, fabrication techniques, especially 3D printing by extrusion and 3D printing by photopolymerization, allow the construction of vessels at a high resolution with diameters in the desired range. Strategies to fabricate of stable tubular structures with defined channels will also be discussed. This paper provides an overview of the many advances in blood vessel engineering and combinations of different fabrication techniques up to the present time.

Directly coaxial bioprinting of 3D vascularized tissue using novel bioink based on decellularized human amniotic membrane

Despite several progressions in the biofabrication of large-scale engineered tissues, direct biopri nting of perfusable three-dimensional (3D) vasculature remained unaddressed. Developing a feasible method to generate cell-laden thick tissue with an effective vasculature network to deliver oxygen and nutrient is crucial for preventing the formation of necrotic spots and tissue death. In this study, we developed a novel technique to directly bioprint 3D cell-laden prevascularized construct. We developed a novel bioink by mixing decellularized human amniotic membrane (dHAM) and alginate (Alg) in various ratios. The bioink with encapsulated human vein endothelial cells (HUVECs) and a crosslinker, CaCl2, were extruded via sheath and core nozzle respectively to directly bioprint a perfusable 3D vasculature construct. The various concentration of bioink was assessed from several aspects like biocompatibility, porosity, swelling, degradation, and mechanical characteristics, and accordingly, optimized concentration was selected (Alg 4 %w/v - dHAM 0.6 %w/v). Then, the crosslinked bioink without microchannel and the 3D bioprinted construct with various microchannel distances (0, 1.5 mm, 3 mm) were compared. The 3D bioprinted construct with a 1.5 mm microchannels distance demonstrated superiority owing to its 492 ± 18.8 % cell viability within 14 days, excellent tubulogenesis, remarkable expression of VEGFR-2 which play a crucial role in endothelial cell proliferation, migration, and more importantly angiogenesis, and neovascularization. This perfusable bioprinted construct also possess appropriate mechanical stability (32.35 ± 5 kPa Young's modulus) for soft tissue. Taking these advantages into the account, our new bioprinting method possesses a prominent potential for the fabrication of large-scale prevascularized tissue to serve for regenerative medicine applications like implantation, drug-screening platform, and the study of mutation disease.

Plant-Derived Biomaterials and Their Potential in Cardiac Tissue Repair

Cardiovascular disease remains the leading cause of mortality worldwide. The inability of cardiac tissue to regenerate after an infarction results in scar tissue formation, leading to cardiac dysfunction. Therefore, cardiac repair has always been a popular research topic. Recent advances in tissue engineering and regenerative medicine offer promising solutions combining stem cells and biomaterials to construct tissue substitutes that could have functions similar to healthy cardiac tissue. Among these biomaterials, plant-derived biomaterials show great promise in supporting cell growth due to their inherent biocompatibility, biodegradability, and mechanical stability. More importantly, plant-derived materials have reduced immunogenic properties compared to popular animal-derived materials (e.g., collagen and gelatin). In addition, they also offer improved wettability compared to synthetic materials. To date, limited literature is available to systemically summarize the progression of plant-derived biomaterials in cardiac tissue repair. Herein, this paper highlights the most common plant-derived biomaterials from both land and marine plants. The beneficial properties of these materials for tissue repair are further discussed. More importantly, the applications of plant-derived biomaterials in cardiac tissue engineering, including tissue-engineered scaffolds, bioink in 3D biofabrication, delivery vehicles, and bioactive molecules, are also summarized using the latest preclinical and clinical examples.

Characterization and Optimization of Injectable In Situ Crosslinked Chitosan-Genipin Hydrogels

In recent years, there has been an increased interest in injectable, in situ crosslinking hydrogels due to their minimally invasive application and ability to conform to their environment. Current in situ crosslinking chitosan hydrogels are either mechanically robust with poor biocompatibility and limited biodegradation due to toxic crosslinking agents or the hydrogels are mechanically weak and undergo biodegradation too rapidly due to insufficient crosslinking. Herein, the authors developed and characterized a thermally-driven, injectable chitosan-genipin hydrogel capable of in situ crosslinking at 37 °C that is mechanically robust, biodegradable, and maintain high biocompatibility. The natural crosslinker genipin is utilized as a thermally-driven, non-toxic crosslinking agent. The chitosan-genipin hydrogel's crosslinking kinetics, injectability, viscoelasticity, swelling and pH response, and biocompatibility against human keratinocyte cells are characterized. The developed chitosan-genipin hydrogels are successfully crosslinked at 37 °C, demonstrating temperature sensitivity. The hydrogels maintained a high percentage of swelling over several weeks before degrading in biologically relevant environments, demonstrating mechanical stability while remaining biodegradable. Long-term cell viability studies demonstrated that chitosan-genipin hydrogels have excellent biocompatibility over 7 days, including during the hydrogel crosslinking phase. Overall, these findings support the development of an injectable, in situ crosslinking chitosan-genipin hydrogel for minimally invasive biomedical applications.

Optimization of 3D printing and in vitro characterization of alginate/gelatin lattice and angular scaffolds for potential cardiac tissue engineering

Background: Engineering cardiac tissue that mimics the hierarchical structure of cardiac tissue remains challenging, raising the need for developing novel methods capable of creating structures with high complexity. Three-dimensional (3D)-printing techniques are among promising methods for engineering complex tissue constructs with high precision. By means of 3D printing, this study aims to develop cardiac constructs with a novel angular structure mimicking cardiac architecture from alginate (Alg) and gelatin (Gel) composite. The 3D-printing conditions were optimized and the structures were characterized in vitro, with human umbilical vein endothelial cells (HUVECs) and cardiomyocytes (H9c2 cells), for potential cardiac tissue engineering. Methods: We synthesized the composites of Alg and Gel with varying concentrations and examined their cytotoxicity with both H9c2 cells and HUVECs, as well as their printability for creating 3D structures of varying fibre orientations (angular design). The 3D-printed structures were characterized in terms of morphology by both scanning electron microscopy (SEM) and synchrotron radiation propagation-based imaging computed tomography (SR-PBI-CT), and elastic modulus, swelling percentage, and mass loss percentage as well. The cell viability studies were conducted via measuring the metabolic activity of the live cells with MTT assay and visualizing the cells with live/dead assay kit. Results: Among the examined composite groups of Alg and Gel, two combinations with ratios of 2 to 1 and 3 to 1 (termed as Alg2Gel1 and Alg3Gel1) showed the highest cell survival; they accordingly were used to fabricate two different structures: a novel angular and a conventional lattice structure. Scaffolds made of Alg3Gel1 showed higher elastic modulus, lower swelling percentage, less mass loss, and higher cell survival compared to that of Alg2Gel1. Although the viability of H9c2 cells and HUVECs on all scaffolds composed of Alg3Gel1 was above 99%, the group of the constructs with the angular design maintained significantly more viable cells compared to other investigated groups. Conclusion: The group of angular 3D-ptinted constructs has illustrated promising properties for cardiac tissue engineering by providing high cell viability for both endothelial and cardiac cells, high mechanical strength as well as appropriate swelling, and degradation properties during 21 days of incubation. Statement of Significance: 3D-printing is an emerging method to create complex constructs with high precision in a large scale. In this study, we have demonstrated that 3D-printing can be used to create compatible constructs from the composite of Alg and Gel with endothelial cells and cardiac cells. Also, we have demonstrated that these constructs are able to enhance the viability of cardiac and endothelial cells via creating a 3D structure mimicking the alignment and orientation of the fibers in the native heart.

Biomaterial-based 3D bioprinting strategy for orthopedic tissue engineering

The advent of three-dimensional (3D) bioprinting has enabled impressive progress in the development of 3D cellular constructs to mimic the structural and functional characteristics of natural tissues. Bioprinting has considerable translational potential in tissue engineering and regenerative medicine. This review highlights the rational design and biofabrication strategies of diverse 3D bioprinted tissue constructs for orthopedic tissue engineering applications. First, we elucidate the fundamentals of 3D bioprinting techniques and biomaterial inks and discuss the basic design principles of bioprinted tissue constructs. Next, we describe the rationale and key considerations in 3D bioprinting of tissues in many different aspects. Thereafter, we outline the recent advances in 3D bioprinting technology for orthopedic tissue engineering applications, along with detailed strategies of the engineering methods and materials used, and discuss the possibilities and limitations of different 3D bioprinted tissue products. Finally, we summarize the current challenges and future directions of 3D bioprinting technology in orthopedic tissue engineering and regenerative medicine. This review not only delineates the representative 3D bioprinting strategies and their tissue engineering applications, but also provides new insights for the clinical translation of 3D bioprinted tissues to aid in prompting the future development of orthopedic implants. STATEMENT OF SIGNIFICANCE: 3D bioprinting has driven major innovations in the field of tissue engineering and regenerative medicine; aiming to develop a functional viable tissue construct that provides an alternative regenerative therapy for musculoskeletal tissue regeneration. 3D bioprinting-based biofabrication strategies could open new clinical possibilities for creating equivalent tissue substitutes with the ability to customize them to meet patient demands. In this review, we summarize the significance and recent advances in 3D bioprinting technology and advanced bioinks. We highlight the rationale for biofabrication strategies using 3D bioprinting for orthopedic tissue engineering applications. Furthermore, we offer ample perspective and new insights into the current challenges and future direction of orthopedic bioprinting translation research.

Decellularized bovine ovarian niche restored the function of cumulus and endothelial cells

Objective:

Recently, the decellularization technique is introduced as one of the tissue engineering procedures for the treatment of various deficiencies. Here, we aimed to assess the dynamic activity of CCs and HUVECs within decellularized bovine ovarian tissue transplanted subcutaneously in rats. Ovarian tissue was decellularized using a cocktail consisting of different chemicals, and the efficiency of decellularization was assessed using hematoxylin-eosin and DAPI staining. The cell survival was evaluated using an LDH leakage assay. Thereafter, decellularized samples were recellularized using HUVECs and CCs, encapsulated inside alginate (1.2%)-gelatin, (1%) hydrogel, and transplanted subcutaneously to rats. The existence of CD31- and estrogen-positive cells was assessed using immunohistochemistry staining.

Results:

Bright-field imaging and DAPI staining revealed the lack of nuclei with naive matrix structure in ovarian tissue subjected to decellularization protocol. SEM imaging revealed a normal matrix in decellularized ovaries. LDH assay showed a lack of cytotoxicity for CCs after 7-days compared to the control group. Immunohistochemistry staining showed both CD31- and estrogen-positive cells in CCs + HUVECs compared to the CCs group. CD31 cells appeared with flattened morphology aligned with matrix fibers. The existence of estrogen and CD31 positive cells showed the efficiency of decellularized ovarian tissue to restore cellular function and activity.

Collagen and nano-hydroxyapatite interactions in alginate-based microcapsule provide an appropriate osteogenic microenvironment for modular bone tissue formation

The addition of nano-hydroxyapatite (nHA) and collagen (Col) to the alginate (Alg) microcapsule hydrogel reduced swelling and degradation ratios while the compressive strength increased compared to Alg, Alg-Col, and Alg-nHA groups. MTT assay and Calcein-AM staining revealed an enhanced MG-63 osteoblasts viability in the Alg-nHA-Col hydrogel compared to the other groups. SEM showed the attachment of MG-63 osteoblasts inside Alg-Col hydrogels. Non-significant differences were found in antioxidant capacity of cells inside the Alg-nHA-Col hydrogel compared to the Alg group. Hematoxylin-Eosin staining showed the distribution of MG-63 osteoblasts inside microspheres. Calcium deposits, alkaline phosphatase (ALP) activity with the increase of intracellular calcium were found in Alg-nHA-Col group. Western blotting showed that levels of osteocalcin, ColA2, Sox-9, and ColA1 also significantly increased compared to the Alg, Alg-Col, Alg-nHA groups. The present study demonstrated that the addition of mineral nHA and protein (Col) into the Alg improves osteogenic potential and provides a 3D platform for modular bone tissue engineering.

Biodegraded PCl and gelatin fabricated vascular patch in rat aortic and inferior vena cava angioplasty

Novel synthetic prosthesis materials for patch angioplasty are continuously under development and optimization. When a nonwoven-based gelatin membrane is coupled with an electrospun layer of polycaprolactone (PCL), these biohybrid polymer membranes (BHMs) possess higher mechanical properties in aqueous environments. We hypothesized that BHMs can also be used as vascular patches, and we tested our hypothesis in a rat IVC venoplasty and aortic arterioplasty model. Patch venoplasty and arterioplasty were performed in SD rats (200 g), the patches were harvested at day 14, and samples were analyzed by immunohistochemistry and immunofluorescence. The BHM patches were almost degraded, with few parts remaining after 14 days. There was a line of CD34- and nestin-positive cells on the endothelium, with some cells were CD34 and nestin dual-positive, macrophages and leukocytes also participated in the patch healing process. There were PCNA-positive cells in the neointima and peri-patch area, with some cells were also PCNA and α-actin dual-positive. Arterial neointimal endothelial cells were Ephrin-B2- and dll-4-positive, and venous neointimal endothelial cells were Eph-B4- and COUP-TFII-positive. BHM shares a similar healing process like other patch materials, and BHM may have potential applications in vascular surgery.

Three-dimensional printing of cell-laden microporous constructs using blended bioinks

Hydrogels such as alginate and gelatin have shown potential as biomaterials in various three-dimensional (3D) bioprinting applications. However, parameters such as viscosity, porosity, and printability influence the performance of hydrogel-based biomaterials, and there are limited characterization studies conducted on the behavior of these constructs. In this work, a syringe-based extrusion bioprinter was used to print 3D constructs with bioink composed of various concentrations of alginate and gelatin along with fibrinogen and human umbilical vein endothelial cells. Instead of crosslinking the gelatin, the gelatin was left uncrosslinked to provide microporosity within the system that can impact the cellular response. Mechanical and biochemical characterization was performed to evaluate the structural stability and integrity of the printed constructs along with viability of embedded cells. Bioprinted constructs of a higher total concentration of alginate and gelatin yielded better stability and structural integrity after culture. More importantly, higher amounts of gelatin (i.e., 1:9 instead of 2:3 alginate:gelatin) were shown to improve printability, which is different than most studies that instead use alginate to improve printability. In addition, higher amounts of gelatin impacted the changes in surface morphological features of the constructs after incubation, and ultimately improved biocompatibility with our system. Overall, this study demonstrated that an uncrosslinked gelatin system can provide flexible printing parameters and surface morphologies, but careful control over the printing parameters may be required. The bioink concentration of 10% (w/v) with minimum alginate and higher gelatin concentration exhibited the best printability, cell survival, and viability.

Biomaterials for Cell-Surface Engineering and Their Efficacy

Literature in the field of stem cell therapy indicates that, when stem cells in a state of single-cell suspension are injected systemically, they show poor in vivo survival, while such cells show robust cell survival and regeneration activity when transplanted in the state of being attached on a biomaterial surface. Although an attachment-deprived state induces anoikis, when cell-surface engineering technology was adopted for stem cells in a single-cell suspension state, cell survival and regenerative activity dramatically improved. The biochemical signal coming from ECM (extracellular matrix) molecules activates the cell survival signal transduction pathway and prevents anoikis. According to the target disease, various therapeutic cells can be engineered to improve their survival and regenerative activity, and there are several types of biomaterials available for cell-surface engineering. In this review, biomaterial types and application strategies for cell-surface engineering are presented along with their expected efficacy.

Phenolated alginate-collagen hydrogel induced chondrogenic capacity of human amniotic mesenchymal stem cells

Horseradish peroxidase (HRP)-catalyzed hydrogels are considered to be an important platform for tissue engineering applications. In this study, we investigated the chondrogenic capacity of phenolated (1.2%) alginate-(0.5%) collagen hydrogel on human amniotic mesenchymal stem cells after 21 days. Using NMR, FTIR analyses, and SEM imaging, we studied the phenolation and structure of alginate-collagen hydrogel. For physicochemical evaluations, gelation time, mechanical properties, swelling, and degradation rate were assessed. The survival rate was monitored using the MTT assay and DAPI staining. Western blotting was performed to measure the chondrogenic differentiation of cells. NMR showed successful phenolation of the alginate-collagen hydrogel. FTIR exhibited the interaction between the functional groups of collagen with phenolated alginate. SEM showed the existence of collagen microfibrils in the alginate-collagen hydrogel. Compared to phenolated alginate, the addition of collagen increased hydrogel elasticity by 10%. Both swelling rate and biodegradability were reduced in the presence of collagen. We noted an increased survival rate in phenolated alginate-collagen compared to the control cells (p < 0.05). Western blotting revealed the increase of chondrocyte-associated proteins such as SOX9 and COL2A1 in phenolated-alginate-collagen hydrogels after 21 days. These data showed that phenolated alginate-collagen hydrogel is an appropriate 3 D substrate to induce chondrogenic capacity of human mesenchymal stem cells.

Application of 3D bioprinting in the prevention and the therapy for human diseases

Rapid development of vaccines and therapeutics is necessary to tackle the emergence of new pathogens and infectious diseases. To speed up the drug discovery process, the conventional development pipeline can be retooled by introducing advanced in vitro models as alternatives to conventional infectious disease models and by employing advanced technology for the production of medicine and cell/drug delivery systems. In this regard, layer-by-layer construction with a 3D bioprinting system or other technologies provides a beneficial method for developing highly biomimetic and reliable in vitro models for infectious disease research. In addition, the high flexibility and versatility of 3D bioprinting offer advantages in the effective production of vaccines, therapeutics, and relevant delivery systems. Herein, we discuss the potential of 3D bioprinting technologies for the control of infectious diseases. We also suggest that 3D bioprinting in infectious disease research and drug development could be a significant platform technology for the rapid and automated production of tissue/organ models and medicines in the near future.

Static and dynamic culture of human endothelial cells encapsulated inside alginate-gelatin microspheres

This study aimed to explore the angiogenesis potential of human endothelial cells encapsulated inside alginate-gelatin microspheres under static and dynamic culture systems after 7 days. Human umbilical vein endothelial cells were encapsulated inside alginate (1%) and gelatin (1.2%) using an electrostatic encapsulation method. Cells were incubated for 7 days in vitro. The cell survival rate was measured using the MTT assay. The expression of VEGFR-2 and von Willebrand factor genes was studied by real-time PCR assay. Using western blot analysis, we monitored the protein contents of VEGFR-2, vWF, and Caspase 3. The levels of SOD and GPx enzymes were calculated using biochemical kits. Angiogenesis potential was assessed using in vitro Matrigel assay. Data showed an increased survival rate in encapsulated cells cultured under the static condition compared to the conventional 2D condition (p < 0.05). The culture of encapsulated cells under a dynamic bioreactor system did not alter cell viability. Compared to the dynamic culture system, the incubation of encapsulated cells in the static culture system swelled the microspheres (p < 0.05). Both dynamic and static culture models increased the expression of VEGFR-2 and von Willebrand factor in encapsulated cells compared to 2D culture (p < 0.05), showing enhanced functional maturation. Data showed a significant increase of vWF and reduction of apoptosis marker Caspase in the dynamic culture system (p < 0.05). The levels of SOD and GPx were significantly increased in dynamic and static culture models as compared to the control 2D group (p < 0.05). In vitro tubulogenesis assay showed significant induction of angiogenesis in dynamic encapsulated HUVECs indicated with a large number of vascular tubes and arborized ECs compared to the control and static encapsulated HUVECs (p < 0.05). The current study suggests a bioreactor dynamic system is a reliable approach, similar to a static condition, for the expansion of encapsulated human ECs in a 3D milieu.

Alginate and alginate composites for biomedical applications

Alginate is an edible heteropolysaccharide that abundantly available in the brown seaweed and the capsule of bacteria such as Azotobacter sp. and Pseudomonas sp. Owing to alginate gel forming capability, it is widely used in food, textile and paper industries; and to a lesser extent in biomedical applications as biomaterial to promote wound healing and tissue regeneration. This is evident from the rising use of alginate-based dressing for heavily exuding wound and their mass availability in the market nowadays. However, alginate also has limitation. When in contact with physiological environment, alginate could gelate into softer structure, consequently limits its potential in the soft tissue regeneration and becomes inappropriate for the usage related to load bearing body parts. To cater this problem, wide range of materials have been added to alginate structure, producing sturdy composite materials. For instance, the incorporation of adhesive peptide and natural polymer or synthetic polymer to alginate moieties creates an improved composite material, which not only possesses better mechanical properties compared to native alginate, but also grants additional healing capability and promote better tissue regeneration. In addition, drug release kinetic and cell viability can be further improved when alginate composite is used as encapsulating agent. In this review, preparation of alginate and alginate composite in various forms (fibre, bead, hydrogel, and 3D-printed matrices) used for biomedical application is described first, followed by the discussion of latest trend related to alginate composite utilization in wound dressing, drug delivery, and tissue engineering applications.

Anti-Angiogenic Efficacy of PSORI-CM02 and the Associated Mechanism in Psoriasis In Vitro and In Vivo

Psoriasis is a chronic proliferative autoimmune dermatologic disease characterised by abnormal angiogenesis. Thus, regulating angiogenesis in the skin is an important treatment strategy for psoriasis. PSORI-CM02, an empirical Chinese medicine formula optimised from Yin Xie Ling, was created by the Chinese medicine specialist, Guo-Wei Xuan. Clinical studies have shown that PSORI-CM02 is safe and effective for the treatment of psoriasis. However, its anti-psoriatic mechanisms remain to be further explored. In this study, we investigated the effects of PSORI-CM02 on angiogenesis in the skin and the underlying mechanisms in IL-17A-stimulated human umbilical vein endothelial cells (HUVECs) and a murine model of imiquimod (IMQ)-induced psoriasis. In vitro, PSORI-CM02 significantly inhibited the proliferation and migration of IL-17A-stimulated HUVECs in a dose-dependent manner. Further, it markedly regulated the antioxidative/oxidative status and inflammation; suppressed the expression of VEGF, VEGFR1, VEGFR2, ANG1, and HIF-1α; and reduced the phosphorylation of MAPK signalling pathway components in IL-17A-stimulated HUVECs. In vivo studies showed that PSORI-CM02 markedly reduced angiogenesis in the skin of mice with IMQ-induced psoriasis, while significantly rebalancing antioxidant/oxidant levels; inhibiting the production of IL-6, TNF-α, IL-17A, and IL-17F; and repressing the synthesis of angiogenic mediators. In addition, PSORI-CM02 markedly reduced the activation of the MAPK signalling pathway in psoriatic skin tissue. Taken together, our results demonstrated that PSORI-CM02 inhibited psoriatic angiogenesis by reducing the oxidative status and inflammation, suppressing the expression of angiogenesis-related molecules, and inhibiting the activation of the MAPK signalling pathway in vitro and in vivo.

Thymoquinone inhibited vasculogenic capacity and promoted mesenchymal-epithelial transition of human breast cancer stem cells

Background

Vasculogenic mimicry (VM) is characterized by the formation of tubular structure inside the tumor stroma. It has been shown that a small fraction of cancer cells, namely cancer stem cells (CSCs), could stimulate the development of vascular units in the tumor niche, leading to enhanced metastasis to the remote sites. This study aimed to study the inhibitory effect of phytocompound, Thymoquinone (TQ), on human breast MDA-MB-231 cell line via monitoring Wnt/PI3K signaling pathway.

Methods

MDA-MB-231 CSCs were incubated with different concentrations of TQ for 48 h. The viability of CSCs was determined using the MTT assay. The combination of TQ and PI3K and Wnt3a inhibitors was examined in CSCs. By using the Matrigel assay, we measured the tubulogenesis capacity. The percent of CD24⁻ CSCs and Rhodamine 123 efflux capacity was studied using flow cytometry analysis. Protein levels of Akt, p-Akt, Wnt3a, vascular endothelial-cadherin (VE-cadherin), and matrix metalloproteinases-2 and -9 (MMP-2 and -9) were detected by western blotting.

Results

TQ decreased the viability of CSCs in a dose-dependent manner. The combination of TQ with PI3K and Wnt3a inhibitors reduced significantly the survival rate compared to the control group (p < 0.05). TQ could blunt the stimulatory effect of vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), fibroblast growth factor (FGF) on CSCs (p < 0.05). The vasculogenic capacity of CSCs was reduced after being-exposed to TQ (p < 0.05). Western blotting revealed the decrease of CSCs metastasis by suppressing MMP-2 and -9. The protein level of VE-cadherin was also diminished in TQ-treated CSCs as compared to the control cell (p < 0.05), indicating inhibition of mesenchymal-endothelial transition (MendT). TQ could suppress Wnt3a and PI3K, which coincided with the reduction of the p-Akt/Akt ratio. TQ had the potential to decrease the number of CD24⁻ CSCs and Rhodamine 123 efflux capacity after 48 h.

Conclusion

TQ could alter the vasculogenic capacity and mesenchymal-epithelial transition of human breast CSCs in vitro. Thus TQ together with anti-angiogenic therapies may be a novel therapeutic agent in the suppression of VM in breast cancer.

An approach for mechanical property optimization of cell-laden alginate-gelatin composite bioink with bioactive glass nanoparticles

Alginate-gelatin (Alg-Gel) composite hydrogel is extensively used in extrusion-based bioprinting. Although Alg-Gel blends possess excellent biocompatibility and printability, poor mechanical properties have hindered its further clinical applications. In this study, a series of design by incorporating bioactive glass nanoparticles (BG) (particle size of 12 and 25 nm) into Alg-Gel hydrogel have been considered for optimizing the mechanical and biological properties. The composite Alg-Gel-BG bioink was biophysically characterized by mechanical tests and bioprinting practice. Biocompatibility of Alg-Gel-BG bioink was then investigated by bioprinting mouse dermal fibroblasts. Mechanical tests showed enhanced stiffness with increasing concentration of incorporated BG. But the maximum concentration of BG was determined 1.0 wt% before blends became too viscous to print. Meanwhile, the incorporation of BG did not affect the highly porous structure and biodegradation of Alg-Gel hydrogel, while the mechanical strength and printability were enhanced. In addition, the cellular proliferation and adhesion in the bioprinted constructs were significantly enhanced by BG (12 nm), while extension was not affected. Therefore, our strategy of incorporating BG in Alg-Gel composite hydrogel represents an easy-to-use approach to the mechanical reinforcement of cell-laden bioink, thus demonstrating their suitability for future applications in extrusion-based bioprinting.

Biofabrication of endothelial cell, dermal fibroblast, and multilayered keratinocyte layers for skin tissue engineering

The skin serves a substantial number of physiological purposes and is exposed to numerous biological and chemical agents owing to its large surface area and accessibility. Yet, current skin models are limited in emulating the multifaceted functions of skin tissues due to a lack of effort on the optimization of biomaterials and techniques at different skin layers for building skin frameworks. Here, we use biomaterial-based approaches and bioengineered techniques to develop a 3D skin model with layers of endothelial cell networks, dermal fibroblasts, and multilayered keratinocytes. Analysis of mechanical properties of gelatin methacryloyl (GelMA)-based bioinks mixed with different portions of alginate revealed bioprinted endothelium could be better modeled to optimize endothelial cell viability with a mixture of 7.5% GelMA and 2% alginate. Matrix stiffness plays a crucial role in modulating produced levels of Pro-Collagen I alpha-1 and matrix metalloproteinase-1 in human dermal fibroblasts and affecting their viability, proliferation, and spreading. Moreover, seeding human keratinocytes with gelatin-coating multiple times proves helpful in reducing culture time to create multilayered keratinocytes while maintaining their viability. The ability to fabricate selected biomaterials for each layer of skin tissues has implications in the biofabrication of skin systems for regenerative medicine and disease modeling.

Alginate Formulations: Current Developments in the Race for Hydrogel-Based Cardiac Regeneration

Cardiovascular diseases, including myocardial infarction (MI), represent the main worldwide cause of mortality and morbidity. In this scenario, to contrast the irreversible damages following MI, cardiac regeneration has emerged as a novel and promising solution for in situ cellular regeneration, preserving cell behavior and tissue cytoarchitecture. Among the huge variety of natural, synthetic, and hybrid compounds used for tissue regeneration, alginate emerged as a good candidate for cellular preservation and delivery, becoming one of the first biomaterial tested in pre-clinical research and clinical trials concerning cardiovascular diseases. Although promising results have been obtained, recellularization and revascularization of the infarcted area present still major limitations. Therefore, the demand is rising for alginate functionalization and its combination with molecules, factors, and drugs capable to boost the regenerative potential of the cardiac tissue. The focus of this review is to elucidate the promising properties of alginate and to highlight its benefits in clinical trials in relation to cardiac regeneration. The definition of hydrogels, the alginate characteristics, and recent biomedical applications are herewith described. Afterward, the review examines in depth the ongoing developments to refine the material relevance in cardiac recovery and regeneration after MI and presents current clinical trials based on alginate.

Porcine arterial ECM hydrogel: Designing an in vitro angiogenesis model for long-term high-throughput research

The field of angiogenesis research provides deep understanding regarding this important process, which plays fundamental roles in tissue development and different abnormalities. In vitro models offer the advantages of low-cost high-throughput research of angiogenesis while sparing animal lives, and enabling the use of human cells. Nevertheless, prevailing in vitro models lack stability and are limited to a few days' assays. This study, therefore, examines the hypothesis that closely mimicking the vascular microenvironment can more reliably support longer angiogenesis processes in vitro. To this end, porcine arterial extracellular matrix (paECM)- a key component of blood vessels-was isolated and processed into a thermally induced hydrogel and characterized in terms of composition, structure, and mechanical properties, thus confirming the preservation of important characteristics of arterial extracellular matrix. This unique hydrogel was further tailored into a three-dimensional model of angiogenesis using endothelial cells and supporting cells, in a configuration that allows high-throughput quantitative analysis of cell viability and proliferation, cell migration, and apoptosis, thus revealing the advantages of paECM over frequently used biomaterials. Markedly, when applied with well-known effectors of angiogenesis, the model measures reflected the expected response, hence validating its efficacy and establishing its potential as a promising tool for the research of angiogenesis.

Three-dimensional cell printing of gingival fibroblast/acellular dermal matrix/gelatin-sodium alginate scaffolds and their biocompatibility evaluation in vitro

Tissue engineering has emerged as a promising approach for soft tissue regeneration. Three-dimensional (3D) cell printing showed great potential for producing cell-encapsulated scaffolds to repair tissue defects. The advantage of 3D cell printing technology is precise cell loading in scaffolds to achieve tissue regeneration instead of only relying on the cells from surrounding tissue or blood. A new acellular dermal matrix/gelatin-sodium alginate (ADM/A/G) scaffold with living gingival fibroblasts was constructed by 3D cell printing technology for potential oral soft tissue regeneration in this study, and the biological characteristics of the 3D cell printing scaffolds were evaluated. The residue of nucleic acid and growth factors in ADM were detected. Three biomaterials were mixed at an appropriate radio with human gingival fibroblasts (hGFs) to prepare bioinks. Two kinds of layer scaffolds were fabricated by 3D cell printing technology. The mechanical strength and degradability of the scaffolds were determined by measuring their compressive modulus and mass loss. CCK-8 assay and calcein-AM/PI staining were conducted to detect the cell proliferation and viability in 3D cell printing scaffolds. The morphology of the hGFs in the scaffolds were observed using SEM and FITC-phalloidin staining. The expression of COL1A1, PECAM1, and VEGF-A of hGFs in the scaffolds were quantified by qRT-PCR. The gelatin-sodium alginate (A/G) scaffolds were used as control group in all experiments. Compared with the control group, 3D cell printing ADM/A/G scaffolds showed better mechanical strength and longer degradation time. The ADM/A/G scaffolds obviously had a better promotion effect on cell proliferation and viability. Most of the hGFs observed had a fully extended spindle morphology in the ADM/A/G scaffolds but oval morphology in the control group. The expression of COL1A1 was significantly higher than in the control group with time, and the expression of PECAM1 and VEGF-A was slightly higher in ADM/A/G scaffolds on day 14. 3D cell printing gingival fibroblast-ADM/A/G scaffolds showed excellent biological properties, which could be potentially useful in oral soft tissue regeneration.

Hollow Alginate-Poly-L-Lysine-Alginate Microspheres Promoted an Epithelial-Mesenchymal Transition in Human Colon Adenocarcinoma Cells

Purpose: Today, there is an urgent need to develop a three-dimentional culture systems mimicking native in vivo condition in order to screen potency of drugs and possibly any genetic alterations in tumor cells. Due to the existence of limitations in animal models, the development of three dimensional systems is highly recommended. To this end, we encapsulated human colon adenocarcinoma cell line HT29 with alginate-poly-L-lysine (Alg-PLL) microspheres and the rate of epithelial-mesenchymal transition was monitored. Methods: Cells were randomly divided into three groups; control, alginate and Alg-PLL. To encapsulate cells, we mixed HT-29 cells (1 × 10⁶ ) with 1 mL of 0.05% PLL and 1% Alg mixture and electrosprayed into CaCl2 solution by using a high-voltage power. Cells from all groups were maintained at 37˚C in a humidified atmosphere containing 5% CO₂ for 7 days. Cell viability was assessed by MTT assay. To monitor the stemness feature, we measured the transcription of genes such as Snail, Zeb, and Vimentin by using real-time PCR analysis. Results: Addition of PLL to Alg in a hallowed state increased the cell survival rate compared to the control and Alg groups (P<0.05). Cells inside Alg-PLL tended to form microcellular aggregates while in Alg microspheres an even distribution of HT-29 cells was found. Real-time PCR analysis showed the up-regulation of Snail, Zeb, and Vimentin in Alg-PLL microspheres compared to the other groups, showing the acquisition of stemness feature (P<0.05). Conclusion: This study showed that hallow Alg-PLL microspheres increased the epithelialmesenchymal transition rate after 7 days in in vitro condition. Such approaches could be touted as appropriate in vitro models for drug screening.

Crocetin promotes angiogenesis in human endothelial cells through PI3K-Akt-eNOS signaling pathway

Previous studies proved the pro-angiogenic effect of Crocetin, a natural carotenoid dicarboxylic acid, in both in vivo and in vitro models. However, the exact mechanism of Crocetin action has not completely been elucidated yet. The current experiment was designed to find the activity of PI3K-Akt-eNOS axis after the treatment of endothelial cells with Crocetin in vitro. Human Umbilical Vein Endothelial Cells (HUVECs) were incubated with various concentrations of Crocetin (1, 5, 25, 50, and 100 µM) over a period of 72 h. Crocetin significantly increased HUVECs viability after 72 h as compared with the control group. We also found that Crocetin promoted the formation of the capillary-like structure compared to the control (p<0.05). Moreover, an improved migration rate and increased MMP-9 activity were observed in HUVECs that received 50 µM Crocetin (p<0.05). Crocetin enhanced the uptake of Ac-LDL which is correlated with increased lipid metabolism. Based on the data from the current experiment, protein level of VEGFR-1, -2 and p-Akt/Akt, p-eNOS/eNOS ratios were increased 72 h after the treatment of HUVECs with Crocetin (p<0.05). In contrast, the transcription level of VEGF was reduced in Crocetin-treated cells. These data demonstrated that Crocetin promotes HUVECs angiogenesis potential by the modulation of VEGF signaling pathway and increased cell viability. The PI3K/Akt/eNOS axis is required for a Crocetin-associated activity in endothelial cells.

Biomaterial aided differentiation and maturation of induced pluripotent stem cells

Engineering/reprogramming differentiated adult somatic cells to gain the ability to differentiate into any type of cell lineage are called as induced pluripotent stem cells (iPSCs). Offering unlimited self-renewal and differentiation potential, these iPSC are aspired to meet the growing demands in the field of regenerative medicine, tissue engineering, disease modeling, nanotechnology, and drug discovery. Biomaterial fabrication with the rapid evolution of technology increased their versatility and utility in regenerative medicine and tissue engineering, revolutionizing the stem cell biology research with the property to guide the process of proliferation, differentiation, and morphogenesis. Combining traditional culture platforms of iPSC with biomaterials aids to overcome the limitations associated with derivation, proliferation, and maturation, thereby could improve the clinical translation of iPSC. The present review discusses in brief about the reprogramming techniques for the derivation iPSC and details on several biomaterial guided differentiation of iPSC to different cell types with specific relevance to tissue engineering/regenerative medicine.

Encapsulation of rat cardiomyoblasts with alginate-gelatin microspheres preserves stemness feature in vitro

INTRODUCTION

The emergence of numerous tissue engineering and regenerative medicine techniques cell encapsulation paves a way to heal and restore the function of various injured tissues mainly cardiovascular system. Here, we aimed to investigate the role of alginate-gelatin encapsulation on the dynamic of rat cardiomyoblasts in vitro.

MATERIALS AND METHODS

Rat cardiomyoblasts cell line H9C2 were enclosed by using alginate-gelatin microspheres and incubated for 7 days. MTT method was used to examine cell viability. The level of genes associated with cardiomyoblasts maturation MYL7, NPPA, NKX2-5, and GATA4 real-time PCR. ELISA was used to measure the protein levels of Bcl-2 and Bax factor post-encapsulation. The level of SOD, GPx, and TAC was detected by biochemical analyses. Western blotting was performed to measure the content of AMP-activated protein kinase.

RESULTS

We found that encapsulation was able to increase the viability of rat cardiomyocytes after 7 days. The decreased level of Bcl-2 (p < 0.001) coincided with non-significant differences in the level of Bax (p > 0.05). The transcription level of all genes MYL7, NPPA, NKX2-5, and GATA4 were found to down-regulate compared to the control non-treated cells (p < 0.05). No significant differences were found regarding the level of SOD, GPx, and TAC compared to the control (p>0.05). According to western blotting, revealed a reduced level of AMPK following 7-day incubation of rat cardiomyoblasts (p < 0.05).

CONCLUSION

Data confirmed that the encapsulation of rat cardiomyoblasts with alginate-gelatin microspheres maintained the cells multipotentiality.

Cell-Surface Engineering for Advanced Cell Therapy

Stem cells opened great opportunity to overcome diseases that conventional therapy had only limited success. Use of scaffolds made from biomaterials not only helps handling of stem cells for delivery or transplantation but also supports enhanced cell survival. Likewise, cell encapsulation can provide stability for living animal cells even in a state of separateness. Although various chemical reactions were tried to encapsulate stolid microbial cells such as yeasts, a culture environment for the growth of animal cells allows only highly biocompatible reactions. Therefore, the animal cells were mostly encapsulated in hydrogels, which resulted in enhanced cell survival. Interestingly, major findings of chemistry on biological interfaces demonstrate that cell encapsulation in hydrogels have a further a competence for modulating cell characteristics that can go beyond just enhancing the cell survival. In this review, we present a comprehensive overview on the chemical reactions applied to hydrogel-based cell encapsulation and their effects on the characteristics and behavior of living animal cells.