Decellularized extracellular matrix-based composite scaffolds for tissue engineering and regenerative medicine

Despite the considerable advancements in fabricating polymeric-based scaffolds for tissue engineering,the clinical transformation of these scaffolds remained a big challenge because of the difficulty of simulating native organs/tissues'microenvironment.As a kind of natural tissue-derived biomaterials,decellularized extracellular matrix(dECM)-based scaffolds have gained attention due to their unique biomimetic properties,providing a specific microenvironment suitable for promoting cell proliferation,migration,attachment and regulating differentiation.The medical applications of dECM-based scaffolds have addressed critical challenges,including poor mechanical strength and insufficient stability.For promoting the reconstruction of damaged tissues or organs,dif-ferent types of dECM-based composite platforms have been designed to mimic tissue microenvironment,including by integrating with natural polymer or/and syntenic polymer or adding bioactive factors.In this review,we summarized the research progress of dECM-based composite scaffolds in regenerative medicine,highlighting the critical challenges and future perspectives related to the medical application of these composite materials。

Decellularized extracellular matrix materials for treatment of ischemic cardiomyopathy

Ischemic cardiomyopathy(ICM)affect millions of patients globally.Decellularized extracellular matrix materials(dECM)have components,microstructure and mechanical properties similar to healthy cardiac tissues,and can be manufactured into various forms of implantable biomaterials including injectable hydrogels or epicardial patches,which have been extensively reported to attenuate pathological left ventricular remodeling and maintain heart function.Recently,dECM medical devices for ICM treatment have been approved for clinical use or studied in clinical trials,exhibiting considerable translation potential.Cells,growth factors and other bioactive agents have been incorporated with different dECM materials to improve the therapeutic outcomes.In addition,more detailed aspects of the biological effects and mechanisms of dECM treatment are being revealed.This review summarized recent advances in dECM materials from variable sources for cardiac repair,including extraction of extracellular matrix,cell integration,smart manufacturing of injectable hydrogels and cardiac patch materials,and their therapeutic applications.Besides,this review provides an outlook on the cutting-edge development directions in the field.

Tailoring the multiscale mechanics of tunable decellularized extracellular matrix (dECM) for wound healing through immunomodulation

With the discovery of the pivotal role of macrophages in tissue regeneration through shaping the tissue immune microenvironment, various immunomodulatory strategies have been proposed to modify traditional biomaterials. Decellularized extracellular matrix (dECM) has been extensively used in the clinical treatment of tissue injury due to its favorable biocompatibility and similarity to the native tissue environment. However, most reported decellularization protocols may cause damage to the native structure of dECM, which undermines its inherent advantages and potential clinical applications. Here, we introduce a mechanically tunable dECM prepared by optimizing the freeze-thaw cycles. We demonstrated that the alteration in micromechanical properties of dECM resulting from the cyclic freeze-thaw process contributes to distinct macrophage-mediated host immune responses to the materials, which are recently recognized to play a pivotal role in determining the outcome of tissue regeneration. Our sequencing data further revealed that the immunomodulatory effect of dECM was induced via the mechnotrasduction pathways in macrophages. Next, we tested the dECM in a rat skin injury model and found an enhanced micromechanical property of dECM achieved with three freeze-thaw cycles significantly promoted the M2 polarization of macrophages, leading to superior wound healing. These findings suggest that the immunomodulatory property of dECM can be efficiently manipulated by tailoring its inherent micromechanical properties during the decellularization process. Therefore, our mechanics-immunomodulation-based strategy provides new insights into the development of advanced biomaterials for wound healing.

Injectable decellularized extracellular matrix hydrogel loaded with exosomes encapsulating curcumin for prevention of cardiac fibrosis after myocardial infarction

Excessive cardiac fibrosis impairs cardiac repair after myocardial infarction(MI).In this work,an in-jectable composite hydrogel integrating natural biomaterials,exosomes,and bioactive molecules is de-veloped to prevent or alleviate cardiac fibrosis.Curcumin,a natural molecule with antifibrotic activity,is encapsulated in the exosomes that are isolated from bone marrow-derived mesenchymal stem cells to enhance its water solubility and bioavailability.These composite exosomes are efficiently internalised by fibroblasts and effectively inhibit their transition to myofibroblasts in vitro.Decellularized porcine cardiac extracellular matrix(dECM)hydrogel is used as the carrier for delivering these composite exosomes to the infarcted myocardium,not only improving the retention of exosomes but also providing mechani-cal support and structural protection.Injection of this hydrogel into the infarcted heart of a mouse MI model leads to a decrease in collagen deposition,alleviation of fibrosis,a reduction in infarct size,and an improvement in cardiac function.The reported composite hydrogel comprising natural materials and biomolecules exhibits good biocompatibility and bioactivity.Altogether,this study demonstrates that the dECM hydrogel is a suitable platform for the local delivery of antifibrotic biomolecule-encapsulating exo-somes to prevent myocardial fibrosis after MI and have great potential for the treatment of MI in clinical settings.

Decellularized extracellular matrix particle-based biomaterials for cartilage repair applications

Cartilage Decellularized ExtraCellular Matrix(dECM)materials have shown promising cartilage regenera-tion capacity due to their chondrogenic bioactivity.However,the limited retention of ECM components and the reduced integrity of functional ECM molecules during traditional decellularization processes im-pair the biomimicry of these materials.The current study aims to fabricate biomimetic materials con-taining decellularized cartilage particles that have an intact molecular structure and native composition as biomaterial inks and hydrogels for cartilage repair.For this,we established a novel two-fraction de-cellularization strategy for the preparation of reconstituted dECM(rdECM)particles by mixing the two-fraction components,as well as a one-fraction decellularization strategy for the preparation of biomimetic dECM(bdECM)particles.Hyaluronic acid-tyramine(THA)hydrogels containing rdECM or bdECM particles were produced and characterized via rheological test,swelling and stability evaluation,and compression test.The results showed that our novel decellularization strategies preserved intact proteoglycans and collagen at a higher retention rate with adequate DNA removal compared to traditional methods of de-cellularization.The addition of rdECM or bdECM particles significantly increased the shear moduli of the THA bioinks while preserving their shear-thinning properties.bdECM particle-embedded THA hydrogels also achieved long-term stability with a swelling ratio of 70%and high retention of glycosaminoglycans and collagen after long-term incubation,while rdECM particle-embedded THA hydrogels showed unsat-isfactory stability as self-standing biomaterials.Compared to pure THA hydrogels,the addition of bdECM particles significantly enhanced the compression moduli.In summary,our decellularization methods are successful in the retention of functional and intact cartilage components with high yield.Both rdECM and bdECM particles can be supplemented in THA bioinks for biomimetic cartilage 3D printing.Hydro-gels with cartilage bdECM particles possess the functional structure and the natural composition of car-tilage ECM,long-term stability,and enhanced mechanical properties,and are promising biomaterials for cartilage repair.

Decellularized extracellular matrix mediates tissue construction and regeneration

Contributing to organ formation and tissue regeneration,extracellular matrix(ECM)constituents provide tissue with three-dimensional(3D)structural integrity and cellular-function regulation.Containing the crucial traits of the cellular microenvironment,ECM substitutes mediate cell–matrix interactions to prompt stem-cell proliferation and differentiation for 3D organoid construction in vitro or tissue regeneration in vivo.However,these ECMs are often applied generically and have yet to be extensively developed for specific cell types in 3D cultures.Cultured cells also produce rich ECM,particularly stromal cells.Cellular ECM improves 3D culture development in vitro and tissue remodeling during wound healing after implantation into the host as well.Gaining better insight into ECM derived from either tissue or cells that regulate 3D tissue reconstruction or organ regeneration helps us to select,produce,and implant the most suitable ECM and thus promote 3D organoid culture and tissue remodeling for in vivo regeneration.Overall,the decellularization methodologies and tissue/cell-derived ECM as scaffolds or cellular-growth supplements used in cell propagation and differentiation for 3D tissue culture in vitro are discussed.Moreover,current preclinical applications by which ECM components modulate the wound-healing process are reviewed.

Decellularized Extracellular Matrix Containing Electrospun Fibers for Nerve Regeneration:A Comparison Between Core–Shell Structured and Preblended Composites

Advanced biomaterial-based strategies for treatment of peripheral nerve injury require precise control over both topological and biological cues for facilitating rapid and directed nerve regeneration.As a highly bioactive and tissue-specifc natural material,decellularized extracellular matrix(dECM)derived from peripheral nerves(decellularized nerve matrix,DNM)has drawn increasing attention in the feld of regenerative medicine,due to its outstanding capabilities in facilitating neurite outgrowth and remyelination.To induce and maintain sufcient topological guidance,electrospinning was conducted for fabrication of axially aligned nanofbers consisting of DNM and poly(ε-caprolactone)(PCL).Core–shell structured fbers were prepared by coaxial electrospinning using DNM as the shell and PCL as the core.Compared to the aligned electrospun fbers using preblended DNM/PCL,the core–shell structured fbers exhibited lower tensile strength,faster degradation,but considerable toughness for nerve guidance conduit preparation and relatively intact fbrous structure after long-term degradation.More importantly,the full DNM surface coverage of the aligned core–shell fbers efectively promoted axonal extension and Schwann cells migration.The DNM contents further triggered neurite bundling and myelin formation toward nerve fber maturation and functionalization.Herein,we not only pursue a multi-functional scafold design for nerve regeneration,a detailed comparison between core–shell structured and preblended electrospinning of DNM/PCL composites was also provided as an applicable paradigm for advanced tissue-engineered strategies using dECM-based biomaterials.

Cardiac tissue-derived extracellular matrix scaffolds for myocardial repair:advantages and challenges

Decellularized extracellular matrix(dECM)derived from myocardium has been widely explored as a nature scaffold for cardiac tissue engineering applications.Cardiac dECM offers many unique advantages such as preservation of organ-specific ECM microstructure and composition,demonstration of tissue-mimetic mechanical properties and retention of biochemical cues in favor of subsequent recellularization.However,current processes of dECM decellularization and recellularization still face many challenges including the need for balance between cell removal and extracellular matrix preservation,efficient recellularization of dECM for obtaining homogenous cell distribution,tailoring material properties of dECM for enhancing bioactivity and prevascularization of thick dECM.This review summarizes the recent progresses of using dECM scaffold for cardiac repair and discusses its major advantages and challenges for producing biomimetic cardiac patch.

Matrix from urine stem cells boosts tissue-specific stem cell mediated functional cartilage reconstruction

Articular cartilage has a limited capacity to self-heal once damaged.Tissue-specific stem cells are a solution for cartilage regeneration;however,ex vivo expansion resulting in cell senescence remains a challenge as a large quantity of high-quality tissue-specific stem cells are needed for cartilage regeneration.Our previous report demonstrated that decellularized extracellular matrix(dECM)deposited by human synovium-derived stem cells(SDSCs),adipose-derived stem cells(ADSCs),urine-derived stem cells(UDSCs),or dermal fibroblasts(DFs)provided an ex vivo solution to rejuvenate human SDSCs in proliferation and chondrogenic potential,particularly for dECM deposited by UDSCs.To make the cell-derived dECM(C-dECM)approach applicable clinically,in this study,we evaluated ex vivo rejuvenation of rabbit infrapatellar fat pad-derived stem cells(IPFSCs),an easily accessible alternative for SDSCs,by the abovementioned C-dECMs,in vivo application for functional cartilage repair in a rabbit osteochondral defect model,and potential cellular and molecular mechanisms underlying this rejuvenation.We found that C-dECM rejuvenation promoted rabbit IPFSCs’cartilage engineering and functional regeneration in both ex vivo and in vivo models,particularly for the dECM deposited by UDSCs,which was further confirmed by proteomics data.RNA-Seq analysis indicated that both mesenchymal-epithelial transition(MET)and inflammation-mediated macrophage activation and polarization are potentially involved in the C-dECM-mediated promotion of IPFSCs’chondrogenic capacity,which needs further investigation.

Decellularized extracellular matrix as scaffold for cancer organoid cultures of colorectal peritoneal metastases

Peritoneal metastases (PM) from colorectal cancer (CRC) are associated with poor survival. The extracellular matrix (ECM) plays a fundamental role in modulating the homing of CRC metastases to the peritoneum. The mechanisms underlying the interactions between metastatic cells and the ECM, however, remain poorly understood, and the number of in vitro models available for the study of the peritoneal metastatic process is limited. Here, we show that decellularized ECM of the peritoneal cavity allows the growth of organoids obtained from PM, favoring the development of three-dimensional (3D) nodules that maintain the characteristics of in vivo PM. Organoids preferentially grow on scaffolds obtained from neoplastic peritoneum, which are characterized by greater stiffness than normal scaffolds. A gene expression analysis of organoids grown on different substrates reflected faithfully the clinical and biological characteristics of the organoids. An impact of the ECM on the response to standard chemotherapy treatment for PM was also observed. The ex vivo 3D model, obtained by combining patient-derived decellularized ECM with organoids to mimic the metastatic niche, could be an innovative tool to develop new therapeutic strategies in a biologically relevant context to personalize treatments.

Three-dimensional breast cancer tumor models based on natural hydrogels:a review

Breast cancer is the most common cancer in women and one of the deadliest cancers worldwide.According to the distribution of tumor tissue,breast cancer can be divided into invasive and non-invasive forms.The cancer cells in invasive breast cancer pass through the breast and through the immune system or systemic circulation to different parts of the body,forming metastatic breast cancer.Drug resistance and distant metastasis are the main causes of death from breast cancer.Research on breast cancer has attracted extensive attention from researchers.In vitro construction of tumor models by tissue engineering methods is a common tool for studying cancer mechanisms and anticancer drug screening.The tumor microenvironment consists of cancer cells and various types of stromal cells,including fibroblasts,endothelial cells,mesenchymal cells,and immune cells embedded in the extracellular matrix.The extracellular matrix contains fibrin proteins(such as types Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅵ,and Ⅹ collagen and elastin)and glycoproteins(such as proteoglycan,laminin,and fibronectin),which are involved in cell signaling and binding of growth factors.The current traditional two-dimensional(2D)tumor models are limited by the growth environment and often cannot accurately reproduce the heterogeneity and complexity of tumor tissues in vivo.Therefore,in recent years,research on three-dimensional(3D)tumor models has gradually increased,especially 3D bioprinting models with high precision and repeatability.Compared with a 2D model,the 3D environment can better simulate the complex extracellular matrix components and structures in the tumor microenvironment.Three-dimensional models are often used as a bridge between 2D cellular level experiments and animal experiments.Acellular matrix,gelatin,sodium alginate,and other natural materials are widely used in the construction of tumor models because of their excellent biocompatibility and non-immune rejection.Here,we review various natural scaffold materials and construction methods involved in 3D tissue-engineered tumor models,as a reference for research in the field of breast cancer.

Chondrogenic priming of human fetal synovium-derived stem cells in an adult stem cell matrix microenvironment

Cartilage defects are a challenge to treat clinically due to the avascular nature of cartilage.Low immunogenicity and extensive proliferation and multidifferentiation potential make fetal stem cells a promising source for regenerative medicine.In this study,we aimed to determine whether fetal synovium-derived stem cells(FSDSCs)exhibited replicative senescence and whether expansion on decellularized extracellular matrix(dECM)deposited by adult SDSCs(AECM)promoted FSDSCs’chondrogenic potential.FSDSCs from passage 2 and 9 were compared for chondrogenic potential,using Alcian blue staining for sulfated glycosaminoglycans(GAGs),biochemical analysis for DNA and GAG amounts,and real-time PCR for chondrogenic genes including ACAN and COL2A1.Passage 3 FSDSCs were expanded for one passage on plastic flasks(PL),AECM,or dECM deposited by fetal SDSCs(FECM).During expansion,cell proliferation was evaluated using flow cytometry for proliferation index,stem cell surface markers,and resistance to hydrogen peroxide.During chondrogenic induction,expanded FSDSCs were evaluated for tri-lineage differentiation capacity.We found that cell expansion enhanced FSDSCs’chondrogenic potential at least up to passage 9.Expansion on dECMs promoted FSDSCs’proliferative and survival capacity and adipogenic differentiation but not osteogenic capacity.AECM-primed FSDSCs exhibited an enhanced chondrogenic potential.

Dual-crosslinked regenerative hydrogel for sutureless long-term repair of corneal defect

Corneal transplantation is the most effective clinical treatment for corneal defects,but it requires precise size of donor corneas,surgical sutures,and overcoming other technical challenges.Postoperative patients may suffer graft rejection and complications caused by sutures.Ophthalmic glues that can long-term integrate with the corneal tissue and effectively repair the focal corneal damage are highly desirable.Herein,a hybrid hydrogel consisting of porcine decellularized corneal stroma matrix(pDCSM)and methacrylated hyaluronic acid(HAMA)was developed through a non-competitive dual-crosslinking process.It can be directly filled into corneal defects with various shapes.More importantly,through formation of interpenetrating network and stable amide bonds between the hydrogel and adjacent tissue,the hydrogel manifested excellent adhesion properties to achieve suture-free repair.Meanwhile,the hybrid hydrogel not only preserved bioactive components from pDCSM,but also exhibited cornea-matching transparency,low swelling ratio,slow degradation,and enhanced mechanical properties,which was capable of withstanding superhigh intraocular pressure.The combinatorial hydrogel greatly improved the poor cell adhesion performance of HAMA,supported the viability,proliferation of corneal cells,and preservation of keratocyte phenotype.In a rabbit corneal stromal defect model,the experimental eyes treated with the hybrid hydrogel remained transparent and adhered intimately to the stroma bed with long-term retention,accelerated corneal re-epithelialization and wound healing.Giving the advantages of high bioactivity,low-cost,and good practicality,the dual-crosslinked hybrid hydrogel served effectively for long-term suture-free treatment and tissue regeneration after corneal defect.

Fabrication of a bio-instructive scaffold conferred with a favorable microenvironment allowing for superior implant osseointegration and accelerated in situ vascularized bone regeneration via type H vessel formation

The potential translation of bio-inert polymer scaffolds as bone substitutes is limited by the lack of neovascularization upon implantation and subsequently diminished ingrowth of host bone,most likely resulted from the inability to replicate appropriate endogenous crosstalk between cells.Human umbilical vein endothelial cell-derived decellularized extracellular matrix(HdECM),which contains a collection of angiocrine biomolecules,has recently been demonstrated to mediate endothelial cells(ECs)-osteoprogenitors(OPs)crosstalk.We employed the HdECM to create a PCL(polycaprolactone)/fibrin/HdECM(PFE)hybrid scaffold.We hypothesized PFE scaffold could reconstitute a bio-instructive microenvironment that reintroduces the crosstalk,resulting in vascularized bone regeneration.Following implantation in a rat femoral bone defect,the PFE scaffold demonstrated early vascular infiltration and enhanced bone regeneration by microangiography(μ-AG)and micro-computational tomography(μ-CT).Based on the immunofluorescence studies,PFE mediated the endogenous angiogenesis and osteogenesis with a substantial number of type H vessels and osteoprogenitors.In addition,superior osseointegration was observed by a direct host bone-PCL interface,which was likely attributed to the formation of type H vessels.The bio-instructive microenvironment created by our innovative PFE scaffold made possible superior osseointegration and type H vessel-related bone regeneration.It could become an alternative solution of improving the osseointegration of bone substitutes with the help of induced type H vessels,which could compensate for the inherent biological inertness of synthetic polymers.