Graphene oxide-modified 3D acellular cartilage extracellular matrix scaffold for cartilage regeneration

An injectable cartilage-coating composite with long-term protection, effective lubrication and chondrocyte nourishment for osteoarthritis treatment

The osteoarthritic (OA) environment within articular cartilage poses significant challenges, resulting in chondrocyte dysfunction and cartilage matrix degradation. While intra-articular injections of anti-inflammatory drugs, biomaterials, or bioactive agents have demonstrated some effectiveness, they primarily provide temporary relief from OA pain without arresting OA progression. This study presents an injectable cartilage-coating composite, comprising hyaluronic acid and decellularized cartilage matrix integrated with specific linker polymers. It enhances the material retention, protection, and lubrication on the cartilage surface, thereby providing an effective physical barrier against inflammatory factors and reducing the friction and shear force associated with OA joint movement. Moreover, the composite gradually releases nutrients, nourishing OA chondrocytes, aiding in the recovery of cellular function, promoting cartilage-specific matrix production, and mitigating OA progression in a rat model. Overall, this injectable cartilage-coating composite offers promising potential as an effective cell-free treatment for OA. STATEMENT OF SIGNIFICANCE: Osteoarthritis (OA) in the articular cartilage leads to chondrocyte dysfunction and cartilage matrix degradation. This study introduces an intra-articular injectable composite material (HDC), composed of decellularized cartilage matrix (dECMs), hyaluronan (HA), and specially designed linker polymers to provide an effective cell-free OA treatment. The linker polymers bind HA and dECMs to form an integrated HDC structure with an enhanced degradation rate, potentially reducing the need for frequent injections and associated trauma. They also enable HDC to specifically coat the cartilage surface, forming a protective and lubricating layer that enhances long-term retention, acts as a barrier against inflammatory factors, and reduces joint movement friction. Furthermore, HDC nourishes OA chondrocytes through gradual nutrient release, aiding cellular function recovery, promoting cartilage-specific matrix production, and mitigating OA progression.

Advancements in tissue engineering for articular cartilage regeneration

Articular cartilage injury is a prevalent clinical condition resulting from trauma, tumors, infection, osteoarthritis, and other factors. The intrinsic lack of blood vessels, nerves, and lymphatic vessels within cartilage tissue severely limits its self-regenerative capacity after injury. Current treatment options, such as conservative drug therapy and joint replacement, have inherent limitations. Achieving perfect regeneration and repair of articular cartilage remains an ongoing challenge in the field of regenerative medicine. Tissue engineering has emerged as a key focus in articular cartilage injury research, aiming to utilize cultured and expanded tissue cells combined with suitable scaffold materials to create viable, functional tissues. This review article encompasses the latest advancements in seed cells, scaffolds, and cytokines. Additionally, the role of stimulatory factors including cytokines and growth factors, genetic engineering techniques, biophysical stimulation, and bioreactor systems, as well as the role of scaffolding materials including natural scaffolds, synthetic scaffolds, and nanostructured scaffolds in the regeneration of cartilage tissues are discussed. Finally, we also outline the signaling pathways involved in cartilage regeneration. Our review provides valuable insights for scholars to address the complex problem of cartilage regeneration and repair.

Enhancing cartilage regeneration and repair through bioactive and biomechanical modification of 3D acellular dermal matrix

Acellular dermal matrix (ADM) shows promise for cartilage regeneration and repair. However, an effective decellularization technique that removes cellular components while preserving the extracellular matrix, the transformation of 2D-ADM into a suitable 3D scaffold with porosity and the enhancement of bioactive and biomechanical properties in the 3D-ADM scaffold are yet to be fully addressed. In this study, we present an innovative decellularization method involving 0.125% trypsin and 0.5% SDS and a 1% Triton X-100 solution for preparing ADM and converting 2D-ADM into 3D-ADM scaffolds. These scaffolds exhibit favorable physicochemical properties, exceptional biocompatibility and significant potential for driving cartilage regeneration in vitro and in vivo. To further enhance the cartilage regeneration potential of 3D-ADM scaffolds, we incorporated porcine-derived small intestinal submucosa (SIS) for bioactivity and calcium sulfate hemihydrate (CSH) for biomechanical reinforcement. The resulting 3D-ADM+SIS scaffolds displayed heightened biological activity, while the 3D-ADM+CSH scaffolds notably bolstered biomechanical strength. Both scaffold types showed promise for cartilage regeneration and repair in vitro and in vivo, with considerable improvements observed in repairing cartilage defects within a rabbit articular cartilage model. In summary, this research introduces a versatile 3D-ADM scaffold with customizable bioactive and biomechanical properties, poised to revolutionize the field of cartilage regeneration.

Effects of mechanical properties of carbon-based nanocomposites on scaffolds for tissue engineering applications: a comprehensive review

Mechanical properties, such as elasticity modulus, tensile strength, elongation, hardness, density, creep, toughness, brittleness, durability, stiffness, creep rupture, corrosion and wear, a low coefficient of thermal expansion, and fatigue limit, are some of the most important features of a biomaterial in tissue engineering applications. Furthermore, the scaffolds used in tissue engineering must exhibit mechanical and biological behaviour close to the target tissue. Thus, a variety of materials has been studied for enhancing the mechanical performance of composites. Carbon-based nanostructures, such as graphene oxide (GO), reduced graphene oxide (rGO), carbon nanotubes (CNTs), fibrous carbon nanostructures, and nanodiamonds (NDs), have shown great potential for this purpose. This is owing to their biocompatibility, high chemical and physical stability, ease of functionalization, and numerous surface functional groups with the capability to form covalent bonds and electrostatic interactions with other components in the composite, thus significantly enhancing their mechanical properties. Considering the outstanding capabilities of carbon nanostructures in enhancing the mechanical properties of biocomposites and increasing their applicability in tissue engineering and the lack of comprehensive studies on their biosafety and role in increasing the mechanical behaviour of scaffolds, a comprehensive review on carbon nanostructures is provided in this study.

Accelerating wound healing: Unveiling synergistic effects of P25/SWCNT/Ag and P25/rGO/Ag nanocomposites within PRP-gelatin scaffold, highlighting the synergistic antimicrobial activity

Wound healing is a multifaceted biological process requiring innovative strategies to enhance efficiency and counter infections. In this groundbreaking study, we investigate the regenerative potential of platelet-rich plasma (PRP) integrated into a gelatin (GLT) scaffold along with nanocomposites of titanium dioxide (TiO2) (P25)/single-walled carbon nanotubes (SWCNTs)/Ag and P25/reduced graphene oxide (rGO)/Ag. Incorporating these advanced materials into the PRP/GLT delivery system aims to optimize the controlled release of growth factors (GFs) and leverage the exceptional properties of nanomaterials for enhanced tissue repair and wound healing outcomes. Antioxidant activity assessment using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity reveals the superior performance of P25/SWCNTs/Ag compared to P25/rGO/Ag. Their synergistic effects are evaluated in conjunction with antibacterial and antifungal antibiotics. Furthermore, the wound healing potential of P25/SWCNTs/Ag and P25/rGO/Ag, combined with PRP/GLT, is examined. Notably, both nanocomposites exhibit promising synergistic effects with gentamicin and fluconazole against pathogenic strains. Significantly, the inclusion of non-activated PRP substantially augments the wound healing efficacy of P25/SWCNTs/Ag on days 3 (p < 0.01) and 15 (p < 0.05). These findings pave the way for advanced wound dressing and therapeutic interventions, capitalizing on the synergistic effects of PRP and nanomaterials, thus ultimately benefiting patients and advancing regenerative medicine.

MXene and Xene: promising frontier beyond graphene in tissue engineering and regenerative medicine

The emergence of 2D nanomaterials (2D NMs), which was initiated by the isolation of graphene (G) in 2004, revolutionized various biomedical applications, including bioimaging and -sensing, drug delivery, and tissue engineering, owing to their unique physicochemical and biological properties. Building on the success of G, a novel class of monoelemental 2D NMs, known as Xenes, has recently emerged, offering distinct advantages in the fields of tissue engineering and regenerative medicine. In this review, we focus on the comparison of G and Xene materials for use in fabricating tissue engineering scaffolds. After a brief introduction to the basic physicochemical properties of these materials, recent representative studies are classified in terms of the engineered tissue, i.e., bone, cartilage, neural, muscle, and skin tissues. We analyze several methods of improving the clinical potential of Xene-laden scaffolds using state-of-the-art fabrication technologies and innovative biomaterials. Despite the considerable advantages of Xene materials, critical concerns, such as biocompatibility, biodistribution and regulatory challenges, should be considered. This review and collaborative efforts should advance the field of Xene-based tissue engineering and enable innovative, effective solutions for use in future tissue regeneration.

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, different 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.

A photocrosslinked methacrylated carboxymethyl chitosan/oxidized locust bean gum double network hydrogel for cartilage repair

Repairing articular cartilage defects is a great challenge due to the poor self-regenerative capability of cartilage. Inspired by active substances found in the natural cartilage extracellular matrix, we used methacrylated carboxymethyl chitosan (MA-CMCS) and oxidized locust bean gum (OLBG) as the hydrogel backbone, and prepared a photocrosslinked dual network hydrogel containing allicin and decellularized cartilage powder (DCP). The rheological, swelling and water retention capacities of MA-CMCS@OLBG-Allicin/DCP (MCOAC) hydrogels were investigated to confirm the successful preparation of hydrogels suitable for cartilage repair. The MCOAC hydrogels showed good antibacterial ability to kill S. aureus and E. coli and anti-inflammatory properties due to the introduction of allicin. Furthermore, MA-CMCS@OLBG-Allicin/DCP hydrogels presented good cytocompatibility due to the addition of DCP, which could promote chondrocyte proliferation and promote the differentiation of BMSCs to chondrocytes. Further studies in vivo demonstrated that the DCP-contained MCOAC hydrogel exhibited superior performance in promoting cartilage tissue growth and wound healing in articular cartilage defects. Thus, the MCOAC hydrogel is a promising cartilage repair hydrogel with potential for clinical use.

Promising New Horizons in Medicine: Medical Advancements with Nanocomposite Manufacturing via 3D Printing

Three-dimensional printing technology has fundamentally revolutionized the product development processes in several industries. Three-dimensional printing enables the creation of tailored prostheses and other medical equipment, anatomical models for surgical planning and training, and even innovative means of directly giving drugs to patients. Polymers and their composites have found broad usage in the healthcare business due to their many beneficial properties. As a result, the application of 3D printing technology in the medical area has transformed the design and manufacturing of medical devices and prosthetics. Polymers and their composites have become attractive materials in this industry because of their unique mechanical, thermal, electrical, and optical qualities. This review article presents a comprehensive analysis of the current state-of-the-art applications of polymer and its composites in the medical field using 3D printing technology. It covers the latest research developments in the design and manufacturing of patient-specific medical devices, prostheses, and anatomical models for surgical planning and training. The article also discusses the use of 3D printing technology for drug delivery systems (DDS) and tissue engineering. Various 3D printing techniques, such as stereolithography, fused deposition modeling (FDM), and selective laser sintering (SLS), are reviewed, along with their benefits and drawbacks. Legal and regulatory issues related to the use of 3D printing technology in the medical field are also addressed. The article concludes with an outlook on the future potential of polymer and its composites in 3D printing technology for the medical field. The research findings indicate that 3D printing technology has enormous potential to revolutionize the development and manufacture of medical devices, leading to improved patient outcomes and better healthcare services.

Evolution of biomimetic ECM scaffolds from decellularized tissue matrix for tissue engineering: A comprehensive review

Tissue engineering is essentially a technique for imitating nature. Natural tissues are made up of three parts: extracellular matrix (ECM), signaling systems, and cells. Therefore, biomimetic ECM scaffold is one of the best candidates for tissue engineering scaffolds. Among the many scaffold materials of biomimetic ECM structure, decellularized ECM scaffolds (dECMs) obtained from natural ECM after acellular treatment stand out because of their inherent natural components and microenvironment. First, an overview of the family of dECMs is provided. The principle, mechanism, advances, and shortfalls of various decellularization technologies, including physical, chemical, and biochemical methods are then critically discussed. Subsequently, a comprehensive review is provided on recent advances in the versatile applications of dECMs including but not limited to decellularized small intestinal submucosa, dermal matrix, amniotic matrix, tendon, vessel, bladder, heart valves. And detailed examples are also drawn from scientific research and practical work. Furthermore, we outline the underlying development directions of dECMs from the perspective that tissue engineering scaffolds play an important role as an important foothold and fulcrum at the intersection of materials and medicine. As scaffolds that have already found diverse applications, dECMs will continue to present both challenges and exciting opportunities for regenerative medicine and tissue engineering.

Recent Advances in Decellularized Matrix-Derived Materials for Bioink and 3D Bioprinting

As an emerging 3D printing technology, 3D bioprinting has shown great potential in tissue engineering and regenerative medicine. Decellularized extracellular matrices (dECM) have recently made significant research strides and have been used to create unique tissue-specific bioink that can mimic biomimetic microenvironments. Combining dECMs with 3D bioprinting may provide a new strategy to prepare biomimetic hydrogels for bioinks and hold the potential to construct tissue analogs in vitro, similar to native tissues. Currently, the dECM has been proven to be one of the fastest growing bioactive printing materials and plays an essential role in cell-based 3D bioprinting. This review introduces the methods of preparing and identifying dECMs and the characteristic requirements of bioink for use in 3D bioprinting. The most recent advances in dECM-derived bioactive printing materials are then thoroughly reviewed by examining their application in the bioprinting of different tissues, such as bone, cartilage, muscle, the heart, the nervous system, and other tissues. Finally, the potential of bioactive printing materials generated from dECM is discussed.

In-situ forming injectable GFOGER-conjugated BMSCs-laden hydrogels for osteochondral regeneration

The collagen-mimetic peptide GFOGER possesses the chondrogenic potential and has been used as a cell adhesion peptide or chondrogenic inducer. Here, we prepared an injectable in situ forming composite hydrogel system comprising methoxy polyethylene glycol-b-polycaprolactone (MPEG-PCL) and GFOGER-conjugated PEG-PCL (GFOGER-PEG-PCL) with various GFOGER concentrations based on our recently patented technology. The conjugation of GFOGER to PEG-PCL was confirmed by ¹H NMR, and the particle size distribution and rheological properties for the sol-gel transition behavior of the samples with respect to the GFOGER content were evaluated systemically. In vitro experiments using rat bone marrow-derived mesenchymal stem cells (BMSCs) revealed that the GFOGER-PEG-PCL hydrogel significantly enhanced expression of integrins (β1, α2, and α11), increased expression of FAK, and induced downstream signaling of ERK and p38. Overexpression of chondrogenic markers suggested that BMSCs have the potential to differentiate into chondrogenic lineages within GFOGER-PEG-PCL samples. In vivo studies using a rat osteochondral defect model revealed that transplanted BMSCs with GFOGER_0.8-PEG-PCL survived at the defect with strong chondrogenic expression after 4 weeks. The stem cell-laden GFOGER_0.8-PEG-PCL hydrogel produced remarkable osteochondral regeneration at 8 weeks of transplantation, as determined by histological findings and micro-CT analysis. The histomorphological score in the GFOGER_0.8-PEG-PCL + BMSCs group was ~1.7-, 2.6-, and 5.3-fold higher than that in the GFOGER_0.8-PEG-PCL, MPEG-PCL, and defect groups, respectively. Taken together, these results provide an important platform for further advanced GFOGER-based stem cell research for osteochondral repair.

Regeneration of articular cartilage defects: Therapeutic strategies and perspectives

Articular cartilage (AC), a bone-to-bone protective device made of up to 80% water and populated by only one cell type (i.e. chondrocyte), has limited capacity for regeneration and self-repair after being damaged because of its low cell density, alymphatic and avascular nature. Resulting repair of cartilage defects, such as osteoarthritis (OA), is highly challenging in clinical treatment. Fortunately, the development of tissue engineering provides a promising method for growing cells in cartilage regeneration and repair by using hydrogels or the porous scaffolds. In this paper, we review the therapeutic strategies for AC defects, including current treatment methods, engineering/regenerative strategies, recent advances in biomaterials, and present emphasize on the perspectives of gene regulation and therapy of noncoding RNAs (ncRNAs), such as circular RNA (circRNA) and microRNA (miRNA).

An Update on Graphene Oxide: Applications and Toxicity

Graphene oxide (GO) has attracted much attention in the past few years because of its interesting and promising electrical, thermal, mechanical, and structural properties. These properties can be altered, as GO can be readily functionalized. Brodie synthesized the GO in 1859 by reacting graphite with KClO3 in the presence of fuming HNO3; the reaction took 3-4 days to complete at 333 K. Since then, various schemes have been developed to reduce the reaction time, increase the yield, and minimize the release of toxic byproducts (NO2 and N2O4). The modified Hummers method has been widely accepted to produce GO in bulk. Due to its versatile characteristics, GO has a wide range of applications in different fields like tissue engineering, photocatalysis, catalysis, and biomedical applications. Its porous structure is considered appropriate for tissue and organ regeneration. Various branches of tissue engineering are being extensively explored, such as bone, neural, dentistry, cartilage, and skin tissue engineering. The band gap of GO can be easily tuned, and therefore it has a wide range of photocatalytic applications as well: the degradation of organic contaminants, hydrogen generation, and CO2 reduction, etc. GO could be a potential nanocarrier in drug delivery systems, gene delivery, biological sensing, and antibacterial nanocomposites due to its large surface area and high density, as it is highly functionalized with oxygen-containing functional groups. GO or its composites are found to be toxic to various biological species and as also discussed in this review. It has been observed that superoxide dismutase (SOD) and reactive oxygen species (ROS) levels gradually increase over a period after GO is introduced in the biological systems. Hence, GO at specific concentrations is toxic for various species like earthworms, Chironomus riparius, Zebrafish, etc.

3D-Printing Graphene Scaffolds for Bone Tissue Engineering

Graphene-based materials have recently gained attention for regenerating various tissue defects including bone, nerve, cartilage, and muscle. Even though the potential of graphene-based biomaterials has been realized in tissue engineering, there are significantly many more studies reporting in vitro and in vivo data in bone tissue engineering. Graphene constructs have mainly been studied as two-dimensional (2D) substrates when biological organs are within a three-dimensional (3D) environment. Therefore, developing 3D graphene scaffolds is the next clinical standard, yet most have been fabricated as foams which limit control of consistent morphology and porosity. To overcome this issue, 3D-printing technology is revolutionizing tissue engineering, due to its speed, accuracy, reproducibility, and overall ability to personalize treatment whereby scaffolds are printed to the exact dimensions of a tissue defect. Even though various 3D-printing techniques are available, practical applications of 3D-printed graphene scaffolds are still limited. This can be attributed to variations associated with fabrication of graphene derivatives, leading to variations in cell response. This review summarizes selected works describing the different fabrication techniques for 3D scaffolds, the novelty of graphene materials, and the use of 3D-printed scaffolds of graphene-based nanoparticles for bone tissue engineering.

Superlarge living hyaline cartilage graft contributed by the scale-changed porous 3D culture system for joint defect repair

It is known that an excellent hyaline cartilage phenotype, an internal microstructure with safe crosslinking and available size flexibility are the key factors of cartilage grafts that allow for clinical application. Living hyaline cartilage grafts (LhCGs) constructed by phase-transfer hydrogel (PTCC) systems were reported to have a hyaline phenotype and bionic microstructure. By employing chondrocytes to secrete matrix in the hydrogel and then removing the material to obtain material-free tissue in vitro, LhCG technology exhibited superior performance in cartilage repair. However, PTCC systems could only produce small-sized LhCGs because of medium delivery limitations, which hinders the clinical application of LhCGs. In this study, we prepared three different noncrosslinked gelatin microspheres with diameters from 200 μm to 500 μm, which replaced the original pore-forming agent. The new PTCC system with the mixed and gradient porous structure was used for the preparation of superlarge LhCGs with a continuous structure and hyaline phenotype. Compared to the original technique, the porous gradient structure promoted nutrient delivery and cartilage matrix secretion. The small size of the microporous structure promoted the rapid formation of matrix junctions. The experimental group with a mixed gradient increased cartilage matrix secretion significantly by more than 50% compared to the that of the control. The LhCG final area reached 7 cm²without obvious matrix stratification in the mixed gradient group. The design of the scale-changed porous PTCC system will make LhCGs more promising for clinical application.

Graphene Oxide–Protein-Based Scaffolds for Tissue Engineering. Recent Advances and Applications

The field of tissue engineering is constantly evolving as it aims to develop bioengineered and functional tissues and organs for repair or replacement. Due to their large surface area and ability to interact with proteins and peptides, graphene oxides offer valuable physiochemical and biological features for biomedical applications and have been successfully employed for optimizing scaffold architectures for a wide range of organs, from the skin to cardiac tissue. This review critically focuses on opportunities to employ protein–graphene oxide structures either as nanocomposites or as biocomplexes and highlights the effects of carbonaceous nanostructures on protein conformation and structural stability for applications in tissue engineering and regenerative medicine. Herein, recent applications and the biological activity of nanocomposite bioconjugates are analyzed with respect to cell viability and proliferation, along with the ability of these constructs to sustain the formation of new and functional tissue. Novel strategies and approaches based on stem cell therapy, as well as the involvement of the extracellular matrix in the design of smart nanoplatforms, are discussed.

Graphene oxide-modified silk fibroin/nanohydroxyapatite scaffold loaded with urine-derived stem cells for immunomodulation and bone regeneration

Background

The invasive and complicated procedures involving the use of traditional stem cells limit their application in bone tissue engineering. Cell-free, tissue-engineered bones often have complex scaffold structures and are usually engineered using several growth factors (GFs), thus leading to costly and difficult preparations. Urine-derived stem cells (USCs), a type of autologous stem cell isolated noninvasively and with minimum cost, are expected to solve the typical problems of using traditional stem cells to engineer bones. In this study, a graphene oxide (GO)-modified silk fibroin (SF)/nanohydroxyapatite (nHA) scaffold loaded with USCs was developed for immunomodulation and bone regeneration.

Methods

The SF/nHA scaffolds were prepared via lyophilization and cross-linked with GO using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxy succinimide (NHS). Scaffolds containing various concentrations of GO were characterized using scanning electron microscopy (SEM), the elastic modulus test, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectrometer (XPS). Examinations of cell adhesion, proliferation, viability, morphology, alkaline phosphatase activity, and osteogenesis-related gene expression were performed to compare the osteogenesis-related biological behaviors of USCs cultured on the scaffolds. The effect of USC-laden scaffolds on the differentiation of macrophages was tested using ELISA, qRT-PCR, and immunofluorescence staining. Subcutaneous implantations in rats were performed to evaluate the inflammatory response of the USC-laden scaffolds after implantation. The scaffolds loaded with USCs were implanted into a cranial defect model in rats to repair bone defects. Micro-computed tomography (μCT) analyses and histological evaluation were performed to evaluate the bone repair effects.

Results

GO modification enhanced the mechanical properties of the scaffolds. Scaffolds containing less than 0.5% GO had good biocompatibility and promoted USC proliferation and osteogenesis. The scaffolds loaded with USCs induced the M2-type differentiation and inhibited the M1-type differentiation of macrophages. The USC-laden scaffolds containing 0.1% GO exhibited the best capacity for promoting the M2-type differentiation of macrophages and accelerating bone regeneration and almost bridged the site of the rat cranial defects at 12 weeks after surgery.

Conclusions

This composite system has the capacity for immunomodulation and the promotion of bone regeneration and shows promising potential for clinical applications of USC-based, tissue-engineered bones.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02634-w.

Advances in Use of Nanomaterials for Musculoskeletal Regeneration

Since the worldwide incidence of bone disorders and cartilage damage has been increasing and traditional therapy has reached its limits, nanomaterials can provide a new strategy in the regeneration of bones and cartilage. The nanoscale modifies the properties of materials, and many of the recently prepared nanocomposites can be used in tissue engineering as scaffolds for the development of biomimetic materials involved in the repair and healing of damaged tissues and organs. In addition, some nanomaterials represent a noteworthy alternative for treatment and alleviating inflammation or infections caused by microbial pathogens. On the other hand, some nanomaterials induce inflammation processes, especially by the generation of reactive oxygen species. Therefore, it is necessary to know and understand their effects in living systems and use surface modifications to prevent these negative effects. This contribution is focused on nanostructured scaffolds, providing a closer structural support approximation to native tissue architecture for cells and regulating cell proliferation, differentiation, and migration, which results in cartilage and bone healing and regeneration.

Carbon-Based Nanomaterials for Bone and Cartilage Regeneration: A Review

As the main load-bearing structure in the human body, bone and cartilage are susceptible to damage in sports and other activities. The repair and regeneration of bone and articular cartilage have been extensively studied in the past decades. Traditional approaches have been widely applied in clinical practice, but the effect varies from person to person and may cause side effects. With the rapid development of tissue engineering and regenerative medicine, various biomaterials show great potential in the regeneration of bone and cartilage. Carbon-based nanomaterials are solid materials with different structures and properties composed of allotropes of carbon, which are classified into zero-, one-, and two-dimensional ones. This Review systemically summarizes the different types of carbon-based nanomaterials, including zero-dimensional (fullerene, carbon dots, nanodiamonds), one-dimensional (carbon nanotubes), and two-dimensional (graphenic materials) as well as their applications in bone, cartilage, and osteochondral regeneration. Current limitations and future perspectives of carbon-based nanomaterials are also discussed.

Combination of graphene oxide and platelet-rich plasma improves tendon-bone healing in a rabbit model of supraspinatus tendon reconstruction

The treatment of rotator cuff tear is one of the major challenges for orthopedic surgeons. The key to treatment is the reconstruction of the tendon-bone interface (TBI). Autologous platelet-rich plasma (PRP) is used as a therapeutic agent to accelerate the healing of tendons, as it contains a variety of growth factors and is easy to prepare. Graphene oxide (GO) is known to improve the physical properties of biomaterials and promote tissue repair. In this study, PRP gels containing various concentrations of GO were prepared to promote TBI healing and supraspinatus tendon reconstruction in a rabbit model. The incorporation of GO improved the ultrastructure and mechanical properties of the PRP gels. The gels containing 0.5 mg/ml GO (0.5 GO/PRP) continuously released transforming growth factor-β1 (TGF-β1) and platelet-derived growth factor (PDGF)-AB, and the released TGF-β1 and PDGF-AB were still at high concentrations, ∼1063.451 pg/ml and ∼814.217 pg/ml, respectively, on the 14th day. In vitro assays showed that the 0.5 GO/PRP gels had good biocompatibility and promoted bone marrow mesenchymal stem cells proliferation and osteogenic and chondrogenic differentiation. After 12 weeks of implantation, the magnetic resonance imaging, micro-computed tomography and histological results indicated that the newly regenerated tendons in the 0.5 GO/PRP group had a similar structure to natural tendons. Moreover, the biomechanical results showed that the newly formed tendons in the 0.5 GO/PRP group had better biomechanical properties compared to those in the other groups, and had more stable TBI tissue. Therefore, the combination of PRP and GO has the potential to be a powerful advancement in the treatment of rotator cuff injuries.

Comparison of chondrogenesis-related biological behaviors between human urine-derived stem cells and human bone marrow mesenchymal stem cells from the same individual

BACKGROUND

Stem cells are the main choice for seed cells in tissue engineering, but using most traditional stem cells requires invasive and complicated procedures. Human urine-derived stem cells (hUSCs) are an alternative stem cell source with the advantages of being isolated noninvasively and repetitively from the same individual. The aim of this study was to compare chondrogenesis-related biological behaviors between hUSCs and human bone marrow mesenchymal stem cells (hBMSCs) from the same individual.

METHODS

hUSCs and hBMSCs were isolated from six patients who underwent iliac bone grafting. Cell morphology, proliferation, colony-forming, migration, and multidifferentiation analyses were performed in vitro. Then, acellular cartilage extracellular matrix (ACM) scaffolds were fabricated for in vivo implantation. The comparisons of cell viability, morphology, proliferation, and chondrogenesis between hUSCs and hBMSCs cultured on scaffolds were performed before implantation. The scaffolds loaded with hUSCs or hBMSCs were implanted into a rabbit knee model to repair cartilage defects. Magnetic resonance imaging (MRI) and micro-computed tomography (μCT) Analyses, inflammation and toxicity assays, gross observation, and histological evaluation were performed to evaluate the cartilage repair effects.

RESULTS

In in vitro experiments, hUSCs had better capacity for proliferation, colony-forming, and migration compared to hBMSCs in the same passage, while hBMSCs had greater osteogenic, adipogenic, and chondrogenic abilities compared to hUSCs in the same passage. Both hUSCs and hBMSCs at passage 3 had the strongest potential for proliferation, colony-forming, and multilineage differentiation compared to cells in other passages. The ACM scaffolds loaded with hUSCs or hBMSCs both significantly promoted the repair of cartilage defects in the rabbit knee model at 12 weeks' postimplantation, and the new tissue was mainly hyaline cartilage. However, there was no significant difference in cartilage repair effects between hUSCs and hBMSCs.

CONCLUSIONS

In in vitro experiments, hUSCs presented better capacity for proliferation, while hBMSCs had greater chondrogenic ability. However, hUSCs and hBMSCs had similar cartilage repair effects in vivo. Results indicated that hUSCs can be a stem cell alternative for cartilage regeneration and provide a powerful platform for cartilage tissue engineering and clinical transformation.

Advances in Drug Delivery Nanosystems Using Graphene-Based Materials and Carbon Nanotubes

Carbon is one of the most abundant elements on Earth. In addition to the well-known crystallographic modifications such as graphite and diamond, other allotropic carbon modifications such as graphene-based nanomaterials and carbon nanotubes have recently come to the fore. These carbon nanomaterials can be designed to help deliver or target drugs more efficiently and to innovate therapeutic approaches, especially for cancer treatment, but also for the development of new diagnostic agents for malignancies and are expected to help combine molecular imaging for diagnosis with therapies. This paper summarizes the latest designed drug delivery nanosystems based on graphene, graphene quantum dots, graphene oxide, reduced graphene oxide and carbon nanotubes, mainly for anticancer therapy.