Three dimensional porous scaffolds derived from collagen, elastin and fibrin proteins orchestrate adipose tissue regeneration

Granular Nanofiber-Hydrogel Composite-Programmed Regenerative Inflammation and Adipose Tissue Formation

The interplay between biomaterials and host immune responses critically determines outcomes in tissue restoration. Recent studies suggest that physicochemical properties of materials can dictate pro-regenerative versus pro-fibrotic responses and have begun to define the key immune cell types and signals governing these divergent effects. This emerging understanding enables the engineering of regenerative biomaterials capable of functional restoration in situ. An injectable nanofiber-hydrogel composite (NHC) microparticles are designed and constructed from cross-linked electrospun collagen nanofiber fragments surface-bonded to the hyaluronic acid hydrogel network via covalent conjugation during the cross-linking process. The collagen nanofiber fragments, acting as the structural reinforcement component, increased the overall storage modulus of the NHC to a level comparable to native soft tissues while maintaining a sufficiently high degree of porosity of the hydrogel phase to allow host cell infiltration following subcutaneous injection of the NHC microparticles. More importantly, the NHC promoted macrophage/monocyte infiltration, migration, and spreading, sustained cell recruitment over time, and enhanced the proangiogenic effect and recruitment of PDGFRα+ perivascular progenitor cells, leading to extensive adipose tissue remodeling. This study demonstrates the regenerative potential of the injectable NHC microgels as an off-the-shelf solution for devastating soft tissue losses.

Polyelectrolyte nanofilms on cell surface can induce brown adipogenic differentiation of DFATs

Obesity and its related health issues significantly burden public health systems. Brown adipose tissue holds promise for addressing metabolic disorders and balancing the body's energy, making it a key research focus. Stimulating brown adipogenesis from stem cells could advance regenerative medicine and healthcare. In our previous research, we discovered that poly-l-lysine (PLL) significantly stimulates brown adipogenesis in three-dimensional differentiation of dedifferentiated fat cells (DFATs) within fibrin gels. In this study, we evaluated polyelectrolyte (PE) nanofilms made of PLL and dextran sulfate, applied directly to DFAT surfaces to improve brown adipogenic differentiation through an innovative approach. This approach involved coating the DFAT surfaces with PE nanofilms, forming a multilayer structure that not only provided a supportive matrix but also facilitated the adsorption of essential molecules like T3 and insulin for brown adipogenesis. DFATs coated with three PE layers and encapsulated in fibrin gel showed a significant increase in the adipogenic marker UCP1 gene expression and content. This PLL-based PE nanofilm coating on DFAT surfaces can be a novel and crucial technology for promoting brown adipogenesis in regenerative medicine and healthcare.

The Effect of Carbodiimide Crosslinkers on Gelatin Hydrogel as a Potential Biomaterial for Gingival Tissue Regeneration

Connective tissue grafts for gingival recession treatment present significant challenges as they require an additional surgical site, leading to increased morbidity, extended operative times, and a more painful postoperative recovery for patients. Gelatin contains the arginine-glycine-aspartic acid (RGD) sequence, which supports cell adhesion and interactions. The development of gelatin hydrogels holds significant promise due to their biocompatibility, ease of customization, and structural resemblance to the extracellular matrix, making them a potential candidate for gingival regeneration. This study aimed to assess the physical and biological properties of crosslinked gelatin hydrogels using EDC/NHS with two crosslinker concentrations (GelCL12 and GelCL24) and compare these to non-crosslinked gelatin. Both groups underwent morphological, rheological, and chemical analysis. Biological assessments were conducted to evaluate human gingival fibroblast (HGF) proliferation, migration, and COL1 expression in response to the scaffolds. The crosslinked gelatin group exhibited greater interconnectivity and better physical characteristics without displaying cytotoxic effects on the cells. FTIR analysis revealed no significant chemical differences between the groups. Notably, the GelCL12 group significantly enhanced HGF migration and upregulated COL1 expression. Overall, GelCL12 met the required physical characteristics and biocompatibility, making it a promising scaffold for future gingival tissue regeneration applications.

Decellularized adipose-derived matrix from Superficial layers of abdominal adipose tissue exhibits superior capacity of adipogenesis compared to deep layers

The adipogenic property of decellularized adipose-derived matrix (DAM) varies widely across reports, making it difficult to make a horizontal comparison between reports and posing challenges for the stable clinical translation of DAM. It is possibly due to differences in donor characteristics, but the exact relationship remains unclear. Despite extensive research on the differences between superficial and deep layers of abdominal subcutaneous fat, a main donor of DAM, little is known about their extracellular matrix (ECM) which is promising in regenerative medicine. In this study, we first confirmed the distinct compositional profiles and adipogenic potential between superficial and deep DAM (S-DAM and D-DAM). Both in vitro and in vivo assays confirmed superior adipogenic induction potential in S-DAM over D-DAM. Total amounts of ECM proteins like collagen and laminin were similar, however, the predominant types differed, with collagen I dominating S-DAM and collagen XIV prevailing in D-DAM. S-DAM was enriched with mitochondrial and immunological proteins, whereas D-DAM featured more neuronal, vascular, muscular, and endocrine-related proteins. More proteins involved in mRNA processing were found in D-DAM, with Protein-Protein Interaction (PPI) analysis revealing HNRNPA2B1, HNRNPA1, and HNRNPC as the most tightly interacting members. These findings not only deepen our comprehension of the structural and functional heterogeneity of adipose tissues but also become one of the reason for the large variability between batches of DAM products, providing guidance for constructing more efficient and stable bio-scaffolds.

Developing fibrin-based biomaterials/scaffolds in tissue engineering

Tissue engineering technology has advanced rapidly in recent years, offering opportunities to construct biologically active tissues or organ substitutes to repair or even enhance the functions of diseased tissues and organs. Tissue-engineered scaffolds rebuild the extracellular microenvironment by mimicking the extracellular matrix. Fibrin-based scaffolds possess numerous advantages, including hemostasis, high biocompatibility, and good degradability. Fibrin scaffolds provide an initial matrix that facilitates cell migration, differentiation, proliferation, and adhesion, and also play a critical role in cell-matrix interactions. Fibrin scaffolds are now widely recognized as a key component in tissue engineering, where they can facilitate tissue and organ defect repair. This review introduces the properties of fibrin, including its composition, structure, and biology. In addition, the modification and cross-linking modes of fibrin are discussed, along with various forms commonly used in tissue engineering. We also describe the biofunctionalization of fibrin. This review provides a detailed overview of the use and applications of fibrin in skin, bone, and nervous tissues, and provides novel insights into future research directions for clinical treatment.

Vaginal Tissue Engineering via Gelatin-Elastin Fiber-Reinforced Hydrogels

The vagina is a fibromuscular tube-shaped organ spanning from the hymenal ring to the cervix that plays critical roles in menstruation, pregnancy, and female sexual health. Vaginal tissue constituents, including cells and extracellular matrix components, contribute to tissue structure, function, and prevention of injury. However, much microstructural function remains unknown, including how the fiber-cell and cell-cell interactions influence macromechanical properties. A deeper understanding of these interactions will provide critical information needed to reduce and prevent vaginal injuries. Our objectives for this work herein are to first engineer a suite of biomaterials for vaginal tissue engineering and second to characterize the performance of these biomaterials in the vaginal microenvironment. We successfully created fiber-reinforced hydrogels of gelatin-elastin electrospun fibers infiltrated with gelatin methacryloyl hydrogels. These composites recapitulate vaginal material properties, including stiffness, and are compatible with the vaginal microenvironment: biocompatible with primary vaginal epithelial cells and in acidic conditions. This work significantly advances progress in vaginal tissue engineering by developing novel materials and developing a state-of-the-art tissue engineered vagina.

Development and characterization of flaxseed mucilage and elastin/collagen biofilms

Flaxseed mucilage (FSM)-based biofilms were prepared with varying compositions of the elastin/collagen (ELN/COL) protein matrix. These biofilms were characterized by using fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), and X-ray diffraction (XRD). The thickness, water solubility, moisture content, transparency, and mechanical properties of biofilms were investigated. The biofilms were observed to be homogeneous and flexible. The addition of 40 % w/w ELN/COL to the FSM biofilms (FSM-ELN/COL biofilms) enhanced the thickness from 0.127 to 0.142 mm, water solubility from 59.30 to 84.60 % and elongation at break from 91.4 to 188.6 %. However, the reductions in the tensile strength from 6.56 to 4.69 MPa and melting point from 140 °C to 134 °C of the biofilms were observed. The transparency value of 40 % w/w FSM-ELN/COL biofilms increased from 5.42 to 7.19 due to the presence of ELN/COL within the FSM matrix that hinders the light transmission passing through the biofilm. FTIR and XRD tests indicated hydrogen bonding and electrostatic interactions occurred between FSM and ELN/COL, giving rise to a good compatibility of the system. FSM-ELN/COL biofilms fabricated in this work had appropriate mechanical and thermal stability, thus the promising potential to be employed as food packaging and coating.

3D Porous Binary Composites of Collagen, Elastin, and Fibrin Proteins Orchestrate Adipose Tissue Regeneration

The objective for this study is to advance the development of a specialized biomaterial that can effectively facilitate the regeneration of adipose tissue. In prior studies, the assessment of collagen (Col), elastin (Ela), and fibrin (Fib) unary scaffolds has been conducted. However, it is important to note that native adipose tissue is comprised of a diverse array of extracellular matrix (ECM) constituents. To mimic this behavior, binary compositions of collagen, elastin, and fibrin are fabricated in a 1:1 ratio, resulting in the formation of Col/Ela, Col/Fib, and Ela/Fib composites through a customized fabrication procedure. The physical properties of these scaffolds are comprehensively analyzed using a range of material characterization techniques. Additionally, the biological properties of the scaffolds are investigated by examining the survival, proliferation, and phenotype of adipose-derived stem cells. Subsequently, the aforementioned binary scaffolds are implanted into a rodent model for 28 days. the explants are analysed through X-ray microtomography, histology, and immunohistochemistry. The findings of the study demonstrate that the utilization of binary combinations of Col/Ela, Col/Fib, and Ela/Fib has a discernible impact on the physical and biological characteristics of the scaffolds. Nevertheless, Ela/Fib exhibits characteristics that make it a suitable candidate for adipogenesis due to its notable upregulation of caveolin-1 expression in both acellular and cellular cohorts. The combination of two natural polymers in this cell-material interaction has significantly enhanced the comprehension of adipogenesis.

Polymer-Metal Bilayer with Alkoxy Groups for Antibacterial Improvement

Many bio-applicable materials, medical devices, and prosthetics combine both polymer and metal components to benefit from their complementary properties. This goal is normally achieved by their mechanical bonding or casting only. Here, we report an alternative easy method for the chemical grafting of a polymer on the surfaces of a metal or metal alloys using alkoxy amine salt as a coupling agent. The surface morphology of the created composites was studied by various microscopy methods, and their surface area and porosity were determined by adsorption/desorption nitrogen isotherms. The surface chemical composition was also examined by various spectroscopy techniques and electrokinetic analysis. The distribution of elements on the surface was determined, and the successful bonding of the metal/alloys on one side with the polymer on the other by alkoxy amine was confirmed. The composites show significantly increased hydrophilicity, reliable chemical stability of the bonding, even interaction with solvent for thirty cycles, and up to 95% less bacterial adhesion for the modified samples in comparison with pristine samples, i.e., characteristics that are promising for their application in the biomedical field, such as for implants, prosthetics, etc. All this uses universal, two-step procedures with minimal use of energy and the possibility of production on a mass scale.

Enhancing Immunomodulatory Function of Mesenchymal Stromal Cells by Hydrogel Encapsulation

Mesenchymal stromal cells (MSCs) showcase remarkable immunoregulatory capabilities in vitro, positioning them as promising candidates for cellular therapeutics. However, the process of administering MSCs and the dynamic in vivo environment may impact the cell-cell and cell-matrix interactions of MSCs, consequently influencing their survival, engraftment, and their immunomodulatory efficacy. Addressing these concerns, hydrogel encapsulation emerges as a promising solution to enhance the therapeutic effectiveness of MSCs in vivo. Hydrogel, a highly flexible crosslinked hydrophilic polymer with a substantial water content, serves as a versatile platform for MSC encapsulation. Demonstrating improved engraftment and heightened immunomodulatory functions in vivo, MSCs encapsulated by hydrogel are at the forefront of advancing therapeutic outcomes. This review delves into current advancements in the field, with a focus on tuning various hydrogel parameters to elucidate mechanistic insights and elevate functional outcomes. Explored parameters encompass hydrogel composition, involving monomer type, functional modification, and co-encapsulation, along with biomechanical and physical properties like stiffness, viscoelasticity, topology, and porosity. The impact of these parameters on MSC behaviors and immunomodulatory functions is examined. Additionally, we discuss potential future research directions, aiming to kindle sustained interest in the exploration of hydrogel-encapsulated MSCs in the realm of immunomodulation.

Effect of radiation sterilization on the ability to induce adipose regeneration in vivo in decellularized adipose-derived matrix

BACKGROUND

Decellularized adipose-derived matrix (DAM), a biological scaffold that can induce adipose regeneration. The balance between its sterilization efficiency and its ability to maintain in situ adipose regeneration should be considered in terminal sterilization. The purpose of this study was to investigate the effects of radiation sterilization of cobalt-60 (60 Co)with different doses on adipogenesis induced by different forms of DAM, so as to reduce radiation dose under the premise of safe and effective sterilization and ensure adipogenesis induced by DAM in vivo.

METHODS

High dose (25 kGy) and low dose (5 kGy) radiation were used to sterilize freeze-dried and wet DAM, respectively. The sterilization efficiency, macro and micro characteristics, mechanical and mechanical properties of DAM were compared, and then implanted into the immunocompromised mice to evaluate the adipose regeneration.

RESULTS

Under the two radiation doses, no microbial growth was found in the freeze-dried and wet DAM sterility tests, and no significant changes were observed in the macro and micro structures. In terms of mechanical properties, the elastic modulus of high dose freeze-dried DAM decreased significantly (p < 0.001). In vivo animal experiments, the freeze-dried DAM irradiated with high dose almost completely lost its function of adipogenesis in vivo. Although the wet DAM irradiated with high dose could induce fat regeneration in the early stage, the adipocyte deformation and atrophy appeared in the later stage. The freeze-dried and wet DAM after low dose irradiation was similar to the wet DAM without irradiation in the blank control, which could maintain excellent adipogenic and angiogenic functions in vivo.

CONCLUSION

High dose 60 Co irradiation can completely destroy the ability of freeze-dried DAM to induce adipose regeneration in situ, while low dose irradiation (5 kGy) can effectively sterilize the DAM without damaging in vivo induced adipose regeneration. Radiation has more damage to freeze-dried DAM than wet DAM in adipogenesis properties.

Viability of Collagen Matrix Grafts Associated with Nanohydroxyapatite and Elastin in Bone Repair in the Experimental Condition of Ovariectomy

Bone lesions have the capacity for regeneration under normal conditions of the bone metabolism process. However, due to the increasing incidence of major traumas and diseases that cause bone-mineral deficiency, such as osteoporosis, scaffolds are needed that can assist in the bone regeneration process. Currently, natural polymeric scaffolds and bioactive nanoparticles stand out. Therefore, the objective of the study was to evaluate the osteoregenerative potential in tibiae of healthy and ovariectomized rats using mineralized collagen and nanohydroxyapatite (nHA) scaffolds associated with elastin. The in-vivo experimental study was performed with 60 20-week-old Wistar rats, distributed into non-ovariectomized (NO) and ovariectomized (O) groups, as follows: Controls (G1-NO-C and G4-O-C); Collagen with nHA scaffold (G2-NO-MSH and G5-O-MSH); and Collagen with nHA and elastin scaffold (G3-NO-MSHC and G6-O-MSHC). The animals were euthanized 6 weeks after surgery and the samples were analyzed by macroscopy, radiology, and histomorphometry. ANOVA and Tukey tests were performed with a 95% CI and a significance index of p < 0.05. In the histological analyses, it was possible to observe new bone formed with an organized and compact morphology that was rich in osteocytes and with maturity characteristics. This is compatible with osteoconductivity in both matrices (MSH and MSHC) in rats with normal conditions of bone metabolism and with gonadal deficiency. Furthermore, they demonstrated superior osteogenic potential when compared to control groups. There was no significant difference in the rate of new bone formation between the scaffolds. Ovariectomy did not exacerbate the immune response but negatively influenced the bone-defect repair process.

Combining decellularized adipose tissue with decellularized adventitia extravascular matrix or small intestinal submucosa matrix for the construction of vascularized tissue-engineered adipose

Adipose tissue is an endocrine organ. It serves many important functions, such as energy storage, hormones secretion, and providing insulation, cushioning and aesthetics to the body etc. Adipose tissue engineering offers a promising treatment for soft tissue defects. Early adipose tissue production and long-term survival are closely associated with angiogenesis. Decellularized matrix has a natural ECM (extracellular matrix) component, good biocompatibility, and low immunogenicity. Therefore, in this study, the injectable composite hydrogels were developed to construct vascularized tissue-engineered adipose by using the pro-angiogenic effects of aortic adventitia extravascular matrix (Adv) or small intestinal submucosa (SIS), and the pro-adipogenic effects of decellularized adipose tissue (DAT). The composite hydrogels were cross-linked by genipin. The adipogenic and angiogenic abilities of composite hydrogels were investigated in vitro, and in a rat dorsal subcutaneous implant model. The results showed that DAT and SIS or Adv 1:1 composite hydrogel promoted the migration and tube formation of endothelial cells. Furthermore, DAT and SIS or Adv 1:1 composite hydrogel enhanced adipogenic differentiation of adipose-derived mesenchymal stem cells (ASCs) through activation of PPARγ and C/EBPα. The in vivo studies further demonstrated that DAT with SIS or Adv in a 1:1 ratio also significantly promoted adipogenesis and angiogenesis. In addition, DAT with SIS or Adv in a 1:1 ratio hydrogel recruited macrophage population with enhanced M2-type macrophage polarization, suggesting a positive effect of inflammatory response on angiogenesis. In conclusion, these data suggest that the composite hydrogels of DAT with SIS or Adv in 1:1 ratio have apparent pro-adiogenic and angiogenic abilities, thus providing a promising cell-free tissue engineering biomaterial with broad clinical applications. STATEMENT OF SIGNIFICANCE: Decellularized adipose tissue (DAT) has emerged as an important biomaterial in adipose tissue regeneration. Early adipose tissue production and long-term survival is tightly related to the angiogenesis. The revascularization of the DAT is a key issue that needs to be solved in adipose regeneration. In this study, the injectable composite hydrogels were developed by using DAT with Adv (aortic adventitia extravascular matrix) or SIS (small intestinal submucosa) in different ratio. We demonstrated that the combination of DAT with SIS or Adv in 1:1 ratio effectively improved the proliferation of adipose stem cells and endothelial cells, and promoted greater adipose regeneration and tissue vascularization as compared to the DAT scaffold. This study provides the potential biomaterial for clinical soft tissue regeneration.

Influence of Diameter and Cyclic Mechanical Stimulation on the Beating Frequency of Myocardial Cell-Laden Fibers

Atrioventricular block (AVB) is a severe disease for pediatric patients. The repetitive operations needed in the case of the pacemaker implantation to maintain the electrical signal at the atrioventricular node (AVN) affect the patient's life quality. In this study, we present a method of biofabrication of multi-cell-laden cylindrical fibrin-based fibers that can restore the electrical signal at the AVN. We used human umbilical vein smooth muscle cells (HUVSMCs), human umbilical vein endothelial cells (HUVECs) and induced pluripotent stem cell cardiomyocytes (iPSC-CMs) cultivated either statically or dynamically to mimic the native AVN. We investigated the influence of cell composition, construct diameter and cyclic stretch on the function of the fibrin hydrogels in vitro. Immunohistochemistry analyses showed the maturity of the iPSC-CMs in the constructs through the expression of sarcomeric alpha actinin (SAA) and electrical coupling through Connexin 43 (Cx43) signal. Simultaneously, the beating frequency of the fibrin hydrogels was higher and easy to maintain whereas the concentration of iPSC-CMs was higher compared with the other types of cylindrical constructs. In total, our study highlights that the combination of fibrin with the cell mixture and geometry is offering a feasible biofabrication method for tissue engineering approaches for the treatment of AVB.

Nanofiber Scaffolds as Drug Delivery Systems Promoting Wound Healing

Nanofiber scaffolds have emerged as a revolutionary drug delivery platform for promoting wound healing, due to their unique properties, including high surface area, interconnected porosity, excellent breathability, and moisture absorption, as well as their spatial structure which mimics the extracellular matrix. However, the use of nanofibers to achieve controlled drug loading and release still presents many challenges, with ongoing research still exploring how to load drugs onto nanofiber scaffolds without loss of activity and how to control their release in a specific spatiotemporal manner. This comprehensive study systematically reviews the applications and recent advances related to drug-laden nanofiber scaffolds for skin-wound management. First, we introduce commonly used methods for nanofiber preparation, including electrostatic spinning, sol-gel, molecular self-assembly, thermally induced phase separation, and 3D-printing techniques. Next, we summarize the polymers used in the preparation of nanofibers and drug delivery methods utilizing nanofiber scaffolds. We then review the application of drug-loaded nanofiber scaffolds for wound healing, considering the different stages of wound healing in which the drug acts. Finally, we briefly describe stimulus-responsive drug delivery schemes for nanofiber scaffolds, as well as other exciting drug delivery systems.

Hydrocolloids of Egg White and Gelatin as a Platform for Hydrogel-Based Tissue Engineering

Innovative materials are needed to produce scaffolds for various tissue engineering and regenerative medicine (TERM) applications, including tissue models. Materials derived from natural sources that offer low production costs, easy availability, and high bioactivity are highly preferred. Chicken egg white (EW) is an overlooked protein-based material. Whilst its combination with the biopolymer gelatin has been investigated in the food technology industry, mixed hydrocolloids of EW and gelatin have not been reported in TERM. This paper investigates these hydrocolloids as a suitable platform for hydrogel-based tissue engineering, including 2D coating films, miniaturized 3D hydrogels in microfluidic devices, and 3D hydrogel scaffolds. Rheological assessment of the hydrocolloid solutions suggested that temperature and EW concentration can be used to fine-tune the viscosity of the ensuing gels. Fabricated thin 2D hydrocolloid films presented globular nano-topography and in vitro cell work showed that the mixed hydrocolloids had increased cell growth compared with EW films. Results showed that hydrocolloids of EW and gelatin can be used for creating a 3D hydrogel environment for cell studies inside microfluidic devices. Finally, 3D hydrogel scaffolds were fabricated by sequential temperature-dependent gelation followed by chemical cross-linking of the polymeric network of the hydrogel for added mechanical strength and stability. These 3D hydrogel scaffolds displayed pores, lamellae, globular nano-topography, tunable mechanical properties, high affinity for water, and cell proliferation and penetration properties. In conclusion, the large range of properties and characteristics of these materials provide a strong potential for a large variety of TERM applications, including cancer models, organoid growth, compatibility with bioprinting, or implantable devices.

Resorbable Biomaterials Used for 3D Scaffolds in Tissue Engineering: A Review

This article provides a thorough overview of the available resorbable biomaterials appropriate for producing replacements for damaged tissues. In addition, their various properties and application possibilities are discussed as well. Biomaterials are fundamental components in tissue engineering (TE) of scaffolds and play a critical role. They need to exhibit biocompatibility, bioactivity, biodegradability, and non-toxicity, to ensure their ability to function effectively with an appropriate host response. With ongoing research and advancements in biomaterials for medical implants, the objective of this review is to explore recently developed implantable scaffold materials for various tissues. The categorization of biomaterials in this paper includes fossil-based materials (e.g., PCL, PVA, PU, PEG, and PPF), natural or bio-based materials (e.g., HA, PLA, PHB, PHBV, chitosan, fibrin, collagen, starch, and hydrogels), and hybrid biomaterials (e.g., PCL/PLA, PCL/PEG, PLA/PEG, PLA/PHB PCL/collagen, PCL/chitosan, PCL/starch, and PLA/bioceramics). The application of these biomaterials in both hard and soft TE is considered, with a particular focus on their physicochemical, mechanical, and biological properties. Furthermore, the interactions between scaffolds and the host immune system in the context of scaffold-driven tissue regeneration are discussed. Additionally, the article briefly mentions the concept of in situ TE, which leverages the self-renewal capacities of affected tissues and highlights the crucial role played by biopolymer-based scaffolds in this strategy.

Unraveling White Adipose Tissue Heterogeneity and Obesity by Adipose Stem/Stromal Cell Biology and 3D Culture Models

The immune and endocrine dysfunctions of white adipose tissue are a hallmark of metabolic disorders such as obesity and type 2 diabetes. In humans, white adipose tissue comprises distinct depots broadly distributed under the skin (hypodermis) and as internal depots (visceral). Depot-specific ASCs could account for visceral and subcutaneous adipose tissue properties, by regulating adipogenesis and immunomodulation. More importantly, visceral and subcutaneous depots account for distinct contributions to obesity and its metabolic comorbidities. Recently, distinct ASCs subpopulations were also described in subcutaneous adipose tissue. Interestingly, the superficial layer closer to the dermis shows hyperplastic and angiogenic capacities, whereas the deep layer is considered as having inflammatory properties similar to visceral. The aim of this focus review is to bring the light of recent discoveries into white adipose tissue heterogeneity together with the biology of distinct ASCs subpopulations and to explore adipose tissue 3D models revealing their advantages, disadvantages, and contributions to elucidate the role of ASCs in obesity development. Recent advances in adipose tissue organoids opened an avenue of possibilities to recreate the main cellular and molecular events of obesity leading to a deep understanding of this inflammatory disease besides contributing to drug discovery. Furthermore, 3D organ-on-a-chip will add reproducibility to these adipose tissue models contributing to their translation to the pharmaceutical industry.

Chitosan-collagen-fibrinogen uncrosslinked scaffolds possessing skin regeneration and vascularization potential

Clinical success of regenerative medicine for treating deep-tissue skin injuries depends on the availability of skin grafts. Though bioengineered constructs are tested clinically, lack of neovascularization provide only superficial healing. Thus constructs, which promotes wound healing and supports vascularization has gained priority in tissue engineering. In this study, chitosan-collagen-fibrinogen (CCF) scaffold was fabricated using freeze-drying method without using any chemical crosslinkers. CCF scaffolds proved cytocompatibility and faster healing in in vitro scratch assay of primary human adult dermal fibroblasts cells with progressively increasing vascular endothelial growth factor-A and reducing vascular endothelial growth factor receptor 1 expressions. Skin regeneration evaluated on in vivo full thickness wound model confirmed faster remodeling with angiogenic signatures in CCF scaffold-implanted mice. Histopathological observations corroborated with stereo-zoom and SS-optical coherence tomography images of wound sites to prove the maturation of healing-bed, after 12 days of CCF implantation. Therefore, it is concluded that CCF scaffolds are promising for skin tissue regeneration and demonstrates pro-angiogenic potential.

Cell-Biomaterial Interactions

In animals, the extracellular matrix (ECM) forms a three-dimensional network occupying the intercellular spaces (interstitial matrix) or serving as physical and biochemical support for cells and tissues (basement membrane) [...].

Technological advances in fibrin for tissue engineering

Fibrin is a promising natural polymer that is widely used for diverse applications, such as hemostatic glue, carrier for drug and cell delivery, and matrix for tissue engineering. Despite the significant advances in the use of fibrin for bioengineering and biomedical applications, some of its characteristics must be improved for suitability for general use. For example, fibrin hydrogels tend to shrink and degrade quickly after polymerization, particularly when they contain embedded cells. In addition, their poor mechanical properties and batch-to-batch variability affect their handling, long-term stability, standardization, and reliability. One of the most widely used approaches to improve their properties has been modification of the structure and composition of fibrin hydrogels. In this review, recent advances in composite fibrin scaffolds, chemically modified fibrin hydrogels, interpenetrated polymer network (IPN) hydrogels composed of fibrin and other synthetic or natural polymers are critically reviewed, focusing on their use for tissue engineering.

Design and Investigation of an Eco-Friendly Wound Dressing Composed of Green Bioresources- Soy Protein, Tapioca Starch, and Gellan Gum

In the fields of biomedicine and tissue engineering, natural polymer-based tissue-engineered scaffolds are used in multiple applications. As a plant-derived polymer, soy protein, containing multiple amino acids, is structurally similar to components of the extra-cellular matrix (ECM) of tissues. It is biological safety provided a good potential to be material for pure natural scaffolds. Moreover, as a protein, the properties of soy protein can be easily adjusted by modifying the functional groups on it. In addition, by blending soy protein with other synthetic and natural polymers, the mechanical characteristics and bioactive behavior of scaffolds can be facilitated for a variety of bio-applications. In this research, soy protein and polysaccharides tapioca starch are used, and gellan gum to develop a protein-based composite scaffold for cell engineering. The morphology and surface chemical composition are characterized via micro-computed tomography (micro-CT), scanning electron microscope (SEM), and fourier-transform infrared (FTIR) spectroscopy. The soy/tapioca/gellan gum (STG) composite scaffolds selectively help the adhesion and proliferation of L929 fibroblast cells while improving the migration of L929 fibroblast cells in STG composite scaffolds as the increase of soy protein proportion of the scaffold. In addition, STG composite scaffolds show great potential in the wound healing model to enhance rapid epithelialization and tissue granulation.

Mechanomimetic 3D Scaffolds as a Humanized In Vitro Model for Ovarian Cancer

The mechanical homeostasis of tissues can be altered in response to trauma or disease, such as cancer, resulting in altered mechanotransduction pathways that have been shown to impact tumor development, progression, and the efficacy of therapeutic approaches. Specifically, ovarian cancer progression is parallel to an increase in tissue stiffness and fibrosis. With in vivo models proving difficult to study, tying tissue mechanics to altered cellular and molecular properties necessitate advanced, tunable, in vitro 3D models able to mimic normal and tumor mechanic features. First, we characterized normal human ovary and high-grade serous (HGSC) ovarian cancer tissue stiffness to precisely mimic their mechanical features on collagen I-based sponge scaffolds, soft (NS) and stiff (MS), respectively. We utilized three ovarian cancer cell lines (OVCAR-3, Caov-3, and SKOV3) to evaluate changes in viability, morphology, proliferation, and sensitivity to doxorubicin and liposomal doxorubicin treatment in response to a mechanically different microenvironment. High substrate stiffness promoted the proliferation of Caov-3 and SKOV3 cells without changing their morphology, and upregulated mechanosensors YAP/TAZ only in SKOV3 cells. After 7 days in culture, both OVCAR3 and SKOV3 decreased the MS scaffold storage modulus (stiffness), suggesting a link between cell proliferation and the softening of the matrix. Finally, high matrix stiffness resulted in higher OVCAR-3 and SKOV3 cell cytotoxicity in response to doxorubicin. This study demonstrates the promise of biomimetic porous scaffolds for effective inclusion of mechanical parameters in 3D cancer modeling. Furthermore, this work establishes the use of porous scaffolds for studying ovarian cancer cells response to mechanical changes in the microenvironment and as a meaningful platform from which to investigate chemoresistance and drug response.

Mesenchymal Stem Cells Isolated from Paediatric Paravertebral Adipose Tissue Show Strong Osteogenic Potential

Mesenchymal stem cells (MSCs) represent the basis of novel clinical concepts in cellular therapy and tissue regeneration. Therefore, the isolation of MSCs from various tissues has become an important endeavour for stem cell biobanking and the development of regenerative therapies. Paravertebral adipose tissue is readily exposed during spinal procedures in children and could be a viable source of stem cells for therapeutic applications. Here, we describe the first case of MSCs isolated from paravertebral adipose tissue (PV-ADMSCs), obtained during a routine spinal surgery on a child. Using quantitative real-time PCR and flow cytometry, we show that PV-ADMSCs have different levels of stem marker expression compared to the MSCs from other sources while having the highest proliferation rate. Furthermore, we evaluate the multipotency of PV-ADMSCs by the three-lineage (adipogenic, osteogenic and chondrogenic) differentiation and compare it to the multipotency of MSCs from other sources. It was found that the PV-ADMSCs have a strong osteogenic potential in particular. Taken together, our data indicate that PV-ADMSCs meet the criteria for successful cell therapy, defined by the International Society for Cellular Therapy (ISCT), and thus, could provide a source of MSCs that is relatively easy to isolate and expand in culture. Due to their strong osteogenic potential, these cells provide a promising basis, especially for orthopaedic applications.