Biocompatibility-on-a-chip: Characterization and evaluation of decellularized tendon extracellular matrix (tdECM) hydrogel for 3D stem cell culture in a microfluidic device

Circadian Rhythm-Regulated ADSC-Derived sEVs and a Triphasic Microneedle Delivery System to Enhance Tendon-to-Bone Healing

Modulating the inflammatory microenvironment to reconstruct the fibrocartilaginous layer while promoting tendon repair is crucial for enhancing tendon-to-bone healing in rotator cuff repair (RCR), a persistent challenge in orthopedics. Small extracellular vesicles (sEVs) hold significant potential to modulate inflammation, yet the efficient production of highly bioactive sEVs remains a substantial barrier to their clinical application. Moreover, achieving minimally invasive local delivery of sEVs to the tendon-to-bone interface presents significant technical difficulties. Herein, the circadian rhythm of adipose-derived stem cells is modulated to increase the yield and enhance the inflammatory regulatory capacity of sEVs. Circadian rhythm-regulated sEVs (CR-sEVs) enhance the cyclic adenosine monophosphate signaling pathway in macrophage (Mφ) via platelet factor 4 delivery, thereby inhibiting Mφ M1 polarization. Subsequently, a triphasic microneedle (MN) scaffold with a tip, stem, and base is designed for the local delivery of CR-sEVs (CR-sEVs/MN) at the tendon-to-bone junction, incorporating tendon-derived decellularized extracellular matrix in the base to facilitate tendon repair. CR-sEVs/MN mitigates inflammation, promotes fibrocartilage regeneration, and enhances tendon healing, thereby improving biomechanical strength and shoulder joint function in a rat RCR model. Combining CR-sEVs with this triphasic microneedle delivery system presents a promising strategy for enhancing tendon-to-bone healing in clinical settings.

Harnessing the potential of hydrogels for advanced therapeutic applications: current achievements and future directions

The applications of hydrogels have expanded significantly due to their versatile, highly tunable properties and breakthroughs in biomaterial technologies. In this review, we cover the major achievements and the potential of hydrogels in therapeutic applications, focusing primarily on two areas: emerging cell-based therapies and promising non-cell therapeutic modalities. Within the context of cell therapy, we discuss the capacity of hydrogels to overcome the existing translational challenges faced by mainstream cell therapy paradigms, provide a detailed discussion on the advantages and principal design considerations of hydrogels for boosting the efficacy of cell therapy, as well as list specific examples of their applications in different disease scenarios. We then explore the potential of hydrogels in drug delivery, physical intervention therapies, and other non-cell therapeutic areas (e.g., bioadhesives, artificial tissues, and biosensors), emphasizing their utility beyond mere delivery vehicles. Additionally, we complement our discussion on the latest progress and challenges in the clinical application of hydrogels and outline future research directions, particularly in terms of integration with advanced biomanufacturing technologies. This review aims to present a comprehensive view and critical insights into the design and selection of hydrogels for both cell therapy and non-cell therapies, tailored to meet the therapeutic requirements of diverse diseases and situations.

Repair Effect of Umbilical Cord Mesenchymal Stem Cells Embedded in Hydrogel on Mouse Insulinoma 6 Cells Injured by Streptozotocin

Umbilical cord mesenchymal stem cells (UC-MSCs) possess the capabilities of differentiation and immune modulation, which endow them with therapeutic potential in the treatment of type 2 diabetes mellitus (T2DM). In this study, to investigate the repair mechanism of UC-MSCs in hydrogel on pancreatic β-cells in diabetes, mouse insulinoma 6 (MIN-6) cells damaged by streptozotocin (STZ) in vitro were used in co-culture with UC-MSCs in hydrogel (UC-MSCs + hydrogel). It was found that UC-MSCs + hydrogel had a significant repair effect on injured MIN-6 cells, which was better than the use of UC-MSCs alone (without hydrogel). After repair, the expression of superoxide dismutase (SOD) and catalase (CAT) as well as the total antioxidant capacity (T-AOC) of the repaired MIN-6 cells were increased, effectively reducing the oxidative stress caused by STZ. In addition, UC-MSCs + hydrogel were able to curb the inflammatory response by promoting the expression of anti-inflammatory factor IL-10 and reducing inflammatory factor IL-1β. In addition, the expression of both nuclear antigen Ki67 for cell proliferation and insulin-related genes such as Pdx1 and MafA was increased in the repaired MIN-6 cells by UC-MSCs + hydrogel, suggesting that the repair effect promotes the proliferation of the injured MIN-6 cells. Compared with the use of UC-MSCs alone, UC-MSCs + hydrogel exhibit superior antioxidant stress resistance against injured MIN-6 cells, better proliferation effects and a longer survival time of UC-MSCs because the porous structure and hydrophilic properties of the hydrogel could affect the growth of cells and slow down their metabolic activities, resulting in a better repair effect on the injured MIN-6 cells.

Macrophage Polarization Dynamics in Biomaterials: Implications for in Vitro Wound Healing

The interaction between biomaterials and the immune system plays a pivotal role in determining the success or failure of implantable devices. Macrophages, as key orchestrators of immune responses, exhibit diverse reactions that influence tissue integration or lead to implant failure. This study focuses on unraveling the intricate relationship between macrophage phenotypes and biomaterials, specifically hydrogels, by employing THP-1 cells as a model. Through a comprehensive investigation using polysaccharide, polymer, and protein-based hydrogels, our research sheds light on how the properties of hydrogels influence macrophage polarization. Phenotypic observations, biochemical assays, surface marker expression, and gene expression profiles collectively demonstrate the differential macrophage polarization abilities of polysaccharide-, polymer-, and protein-based hydrogels. Moreover, our indirect coculture studies reveal that hydrogels fostering M2 polarization exhibit exceptional wound-healing capabilities. These findings highlight the crucial role of the hydrogel microenvironment in adjusting macrophage polarization, offering a fresh avenue for refining biomaterials to bolster advantageous immune responses and improve tissue integration. This research contributes valuable insights for designing biomaterials with tailored properties that can guide macrophage behavior, ultimately improving the overall success of implantable devices.

Biomimetic short fiber reinforced 3-dimensional scaffold for bone tissue regeneration

Bone defects caused by diseases and trauma are considered serious clinical challenges. Autologous and allogeneic transplantations are the most widely used methods to mitigate bone defects. However, transplantation poses risks such as secondary trauma, immune rejection, and disease transmission to patients. Preparing a biologically active bone tissue engineering scaffold as a bone substitute can overcome this problem. In the current study, a PLGA/gelatin (Gel) short fiber-reinforced composite three-dimensional (3D) scaffold was fabricated by electrospinning for bone tissue defect repair. A hybrid scaffold adding inorganic materials hydrotalcite (CaAl-LDH) and osteogenic factors deferoxamine (DFO) based on PLGA and Gel composite filaments was prepared. The structure, swelling, drug release, and compressive resilience performance of the 3D scaffolds in a wet state were characterized and the osteogenic effect of the crosslinked scaffold (C-DLPG) was also investigated. The scaffold has shown the optimum physicochemical attributes which still has 380 kPa stress after a 60% compression cycle and sustainedly released the drug for about twenty days. Moreover, a promisingIn vivoosteogenic performance was noted with better tissue organization. At 8 weeks after implantation, the C-DLPG scaffold could fill the bone defect site, and the new bone area reached 19 mm2. The 3D microfiber scaffold, in this study, is expected to be a promising candidate for the treatment of bone defects in the future.

Harmine and Kaempferol treatment enhances NFATC1 and FOXP3 mediated regulatory T-cells' suppressive capacity in generalized vitiligo

BACKGROUND

Generalized vitiligo (GV) is an autoimmune disease characterized by the progressive loss of melanocytes.

OBJECTIVES

Current study was undertaken to assess in-vitro therapeutic potential of Harmine and Kaempferol for GV.

METHODS

Calcium, calcineurin, NFATC1 levels, cell proliferation were assessed by various kits and ORAI1, PEIZO1, Calcineurin, GSK3B, DYRK1A transcripts and IFN-γ,IL-10,TGF-β protein levels were assessed by qPCR and ELISA in blood and skin biopsy samples from Tregs of 52 patients and 50 controls.

RESULTS

Harmine and Kaempferol treatment enhances Treg suppressive capacity, NFATs and FOXP3 expression in blood and skin Tregs of GV patients (p < 0.05). Furthermore, Harmine and Kaempferol treatment in Tregs increased calcineurin and NFATC1 activity and decreased DYRK1A transcripts in blood and skin Tregs of GV patients(p < 0.05). In-silico analysis revealed that Harmine and Kaempferol might boost Treg suppressive capacity by increasing calcineurin dephosphorylation activity leading to increase NFATs activation and also increase nuclear retention of NFATs by inhibiting DYRK1a phosphorylation activity. Moreover, calcineurin and NFATC1 activity in Tregs were positively correlated with Treg suppressive capacity, NFATC1 and FOXP3 expression (p < 0.05), whereas, DYRK1A transcripts were negatively correlated with Treg suppressive capacity, NFATC1 and FOXP3 expression (p < 0.05). These compounds significantly increased melanocytes' survival and proliferation in Treg:CD4+/CD8+:SK-Mel-28 cell line co-culture system from GV patients (p < 0.0001).

CONCLUSIONS

For the first time the study suggests that Harmine and Kaempferol treated Tregs could control the CD8+ and CD4+T-cells' proliferation and IFN-γ production, leading to melanocytes' survival and proliferation. These compounds may serve as novel Treg-based therapeutics for GV; however, in vivo studies are warranted to assess the safety and efficacy of these compounds.

Impact of various detergent-based immersion and perfusion decellularization strategies on the novel caprine pancreas derived extracellular matrix scaffold

Limited availability of the organs donors has facilitated the establishment of xenogeneic organ sources for transplantation. Numerous studies have decellularized several organs and assessed their implantability in order to provide such organs. Among all the decellularized organs studies for xenotransplantation, the pancreas has garnered very limited amount of research. The presently offered alternatives for pancreas transplantation are unable to liberate patients from donor dependence. The rat and mice pancreas are not of an accurate size for transplantation but can only be used for in-vitro studies mimicking in-vivo immune response in humans, while the porcine pancreas can cause zoonotic diseases as it carries porcine endogenous retrovirus (PERV- A/B/C). Therefore, we propose caprine pancreas as a substitute for these organs, which not only reduces donor dependence but also poses no risk of zoonosis. Upon decellularization the extracellular matrix (ECM) of different tissues responds differently to the detergents used for decellularization at physical and physiological level; this necessitates a comprehensive analysis of each tissue independently. This study investigates the impact of decellularization by ionic (SDS and SDC), non-ionic (Triton X-100 and Tween-20), and zwitterionic detergents (CHAPS). All these five detergents have been used to decellularize caprine pancreas via immersion (ID) and perfusion (PD) set-up. In this study, an extensive comparison of these two configurations (ID and PD) with regard to each detergent has been conducted. The final obtained scaffold with each set-up has been evaluated for the left-over cytosolic content, ECM components like sGAG, collagen, and fibronectin were estimated via Prussian blue and Immunohistochemical staining respectively, and finally for the tensile strength and antimicrobial activity. All the detergents performed consistently superior in PD than in ID. Conclusively, PD with SDS, SDC, and TX-100 successfully decellularizes caprine pancreatic tissue while retaining ECM architecture and mechanical properties. This research demonstrates the viability of caprine pancreatic tissue as a substitute scaffold for porcine organs and provides optimal decellularization protocol for this xenogeneic tissue. This research aims to establish a foundation for further investigations into potential regenerative strategies using this ECM in combination with other factors.

3D bioprinting of tissue constructs employing dual crosslinking of decellularized extracellular matrix hydrogel

Bioprinted tissues are currently being utilized for drug and cosmetic screening mostly, but the long-term goal is to achieve human scale functional tissues and organs for transplantation. Hence, recapitulating the multiscale architecture, 3D structures, and complexity of native tissues is the key to produce bioengineered tissues/organs. Decellularized extracellular matrix (dECM)-based biomaterials are widely being used as bioinks for 3D bioprinting for tissue engineering applications. Their potential to provide excellent biocompatibility for the cells drove researchers to use them extensively. However, the decellularization process involves many detergents and enzymes which may contribute to their loss of mechanical properties. Moreover, thermal gelation of dECM-based hydrogels is typically slow which affects the shape fidelity, printability, and physical properties while printing complex structures with 3D printing. But, thermally gelled dECM hydrogels provide excellent cell viability and functionality. To overcome this, a novel dual crosslinking of unmodified dECM has been proposed in this study to render shape fidelity and enhance cell viability and functionality. The dECM-based bioink can be initially polymerized superficially on exposure to light to achieve immediate stability and can attain further stability upon thermal gelation. This dual crosslinking mechanism can maintain the microenvironment of the structure, hence allowing the printing of stable flexible structures. Optimized concentrations of novel photo crosslinkers have been determined and printing of a few complex-shaped anatomical structures has been demonstrated. This approach of fabricating complex scaffolds employing dual crosslinking can be used for the bioprinting of different complex tissue structures with tissue-specific dECM based bioinks.

3D Bioprintable Hypoxia-Mimicking PEG-Based Nano Bioink for Cartilage Tissue Engineering

As hypoxia plays a significant role in the formation and maintenance of cartilage tissue, aiming to develop native hypoxia-mimicking tissue engineering scaffolds is an efficient method to treat articular cartilage (AC) defects. Cobalt (Co) is documented for its hypoxic-inducing effects in vitro by stabilizing the hypoxia-inducible factor-1α (HIF-1α), a chief regulator of stem cell fate. Considering this, we developed a novel three-dimensional (3D) bioprintable hypoxia-mimicking nano bioink wherein cobalt nanowires (Co NWs) were incorporated into the poly(ethylene glycol) diacrylate (PEGDA) hydrogel system as a hypoxia-inducing agent and encapsulated with umbilical cord-derived mesenchymal stem cells (UMSCs). In the current study, we investigated the impact of Co NWs on the chondrogenic differentiation of UMSCs in the PEGDA hydrogel system. Herein, the hypoxia-mimicking nano bioink (PEGDA+Co NW) was rheologically optimized to bioprint geometrically stable cartilaginous constructs. The bioprinted 3D constructs were evaluated for their physicochemical characterization, swelling-degradation behavior, mechanical properties, cell proliferation, and the expression of chondrogenic markers by histological, immunofluorescence, and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) methods. The results disclosed that, compared to the control (PEGDA) group, the hypoxia-mimicking nano bioink (PEGDA+Co NW) group outperformed in print fidelity and mechanical properties. Furthermore, live/dead staining, double-stranded DNA (dsDNA) content, and glycosaminoglycans (GAGs) content demonstrated that adding low amounts of Co NWs (<20 ppm) into PEGDA hydrogel system supported UMSC adhesion, proliferation, and differentiation. Histological and immunofluorescence staining of the PEGDA+Co NW bioprinted structures revealed the production of type 2 collagen (COL2) and sulfated GAGs, rendering it a feasible option for cartilage repair. It was further corroborated by a significant upregulation of the hypoxia-mediated chondrogenic and downregulation of the hypertrophic/osteogenic marker expression. In conclusion, the hypoxia-mimicking hydrogel system, including PEGDA and Co²⁺ ions, synergistically directs the UMSCs toward the chondrocyte lineage without using expensive growth factors and provides an alternative strategy for translational applications in the cartilage tissue engineering field.

Extracellular matrix-derived scaffolds in constructing artificial ovaries for ovarian failure: a systematic methodological review

STUDY QUESTION

What is the current state-of-the-art methodology assessing decellularized extracellular matrix (dECM)-based artificial ovaries for treating ovarian failure?

SUMMARY ANSWER

Preclinical studies have demonstrated that decellularized scaffolds support the growth of ovarian somatic cells and follicles both in vitro and in vivo.

WHAT IS KNOWN ALREADY

Artificial ovaries are a promising approach for rescuing ovarian function. Decellularization has been applied in bioengineering female reproductive tract tissues. However, decellularization targeting the ovary lacks a comprehensive and in-depth understanding.

STUDY DESIGN SIZE DURATION

PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials were searched from inception until 20 October 2022 to systematically review all studies in which artificial ovaries were constructed using decellularized extracellular matrix scaffolds. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol.

PARTICIPANTS/MATERIALS SETTING METHODS

Two authors selected studies independently based on the eligibility criteria. Studies were included if decellularized scaffolds, regardless of their species origin, were seeded with ovarian cells or follicles. Review articles and meeting papers were removed from the search results, as were articles without decellularized scaffolds or recellularization or decellularization protocols, or control groups or ovarian cells.

MAIN RESULTS AND THE ROLE OF CHANCE

The search returned a total of 754 publications, and 12 papers were eligible for final analysis. The papers were published between 2015 and 2022 and were most frequently reported as coming from Iran. Detailed information on the decellularization procedure, evaluation method, and preclinical study design was extracted. In particular, we concentrated on the type and duration of detergent reagent, DNA and extracellular matrix detection methods, and the main findings on ovarian function. Decellularized tissues derived from humans and experimental animals were reported. Scaffolds loaded with ovarian cells have produced estrogen and progesterone, though with high variability, and have supported the growth of various follicles. Serious complications have not been reported.

LIMITATIONS REASONS FOR CAUTION

A meta-analysis could not be performed. Therefore, only data pooling was conducted. Additionally, the quality of some studies was limited mainly due to incomplete description of methods, which impeded specific data extraction and quality analysis. Several studies that used dECM scaffolds were performed or authored by the same research group with a few modifications, which might have biased our evaluation.

WIDER IMPLICATIONS OF THE FINDINGS

Overall, the decellularization-based artificial ovary is a promising but experimental choice for substituting insufficient ovaries. A generic and comparable standard should be established for the decellularization protocols, quality implementation, and cytotoxicity controls. Currently, decellularized materials are far from being clinically applicable to artificial ovaries.

STUDY FUNDING/COMPETING INTERESTS

This study was funded by the National Natural Science Foundation of China (Nos. 82001498 and 81701438). The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

This systematic review is registered with the International Prospective Register of Systematic Reviews (PROSPERO, ID CRD42022338449).

Enhancement of Fracture Toughness in carbonate doped Hydroxyapatite based nanocomposites: Rietveld analysis and Mechanical behaviour

Highly nanocrystalline carbonated hydroxyapatite (CHAp) is synthesized by hydrothermal technique with four different stoichiometric compositions for microstructural and mechanical analysis. HAp is one of the most biocompatible material and addition of carbonate ions lead to increase in fracture toughness highly required in biomedical applications. The structural properties and its purity as single phase is confirmed by X-ray diffraction. Lattice imperfections and structural defects is investigated using XRD pattern model simulation, i.e. Rietveld's analysis. The substitution of CO₃^2- in HAp structure leads to a decrease in crystallinity which ultimately lessens crystallite size of sample as verified by XRD analysis. FE-SEM micrographs confirms the formation of nanorods with cuboidal morphology and porous structure of HAp and CHAp samples. The particle size distribution histogram validates the constant decrease in size due to carbonate addition. The mechanical testing of prepared samples revealed the increase in mechanical strength from 6.12 MPa to 11.52 MPa due to the addition of carbonate content, which leads to a rise in fracture toughness, a significant property of an implant material from 2.93 kN to 4.22 kN. The cumulative effect of CO₃^2- substitution on HAp structure and mechanical properties has been generalized for the application as biomedical implant material or biomedical smart materials.

Bioengineering strategies for 3D bioprinting of tubular construct using tissue-specific decellularized extracellular matrix

The goal of the current study is to develop an extracellular matrix bioink that could mimic the biochemical components present in natural blood vessels. Here, we have used an innovative approach to recycle the discarded varicose vein for isolation of endothelial cells and decellularization of the same sample to formulate the decellularized extracellular matrix (dECM) bioink. The shift towards dECM bioink observed as varicose vein dECM provides the tissue-specific biochemical factors that will enhance the regeneration capability. Interestingly, the encapsulated umbilical cord mesenchymal stem cells expressed the markers of vascular smooth muscle cells because of the cues present in the vein dECM. Further, in vitro immunological investigation of dECM revealed a predominant M2 polarization which could further aid in tissue remodeling. A novel approach was used to fabricate vascular construct using 3D bioprinting without secondary support. The outcomes suggest that this could be a potential approach for patient- and tissue-specific blood vessel regeneration.