A Novel Approach to Utilize Icariin as Icariin-Derived ECM on Small Intestinal Submucosa Scaffold for Bone Repair

Dynamic profiling of BMSC-dECM reveals accumulation of core matrisome proteins suppresses osteogenic differentiation and bone regeneration

INTRODUCTION

The extracellular matrix (ECM) of bone mesenchymal stem cells (BMSCs) plays a critical role in tissue development and regeneration. Rather than being inert, the ECM exhibits a dynamic structure that determines cell fate.

OBJECTIVES

The aim of this study is to investigate the dynamic composition, functional properties, and underlying mechanisms of BMSC-ECM during osteogenic differentiation. We propose that dynamic alterations in BMSC-ECM, particularly in critical matrix proteins, are essential to regulate osteogenic differentiation and bone regeneration.

METHODS

Dynamic ECM from BMSCs was collected at different time points during culture with or without osteogenic induction, followed by decellularization. A mouse tibial defect model was introduced to assess bone regeneration in vivo. Proteomics was used to analyze the dynamic protein composition pattern, while a comparative transcriptomic analysis further determined the impact of dynamic BMSC-dECM on cellular mRNA profile.

RESULTS

Decellularized ECMs (dECMs) from late noninduced BMSCs exhibited distinct functional properties compared to the other groups. While early noninduced, early osteogenic (Os)-induced and late Os-induced dECMs promoted bone regeneration, late noninduced dECM dramatically inhibited this process. The protein composition of dECMs, rather than the structure or total ECM content, was the key factor determining their dynamic function. Accumulation of core matrisome during noninduced culture resulted in the inhibition of its function. Consistently, the gene expression profiles of replanted BMSCs on early noninduced/Os-induced dECM and late Os-induced dECM were similar, leaving the late noninduced dECM separate. Moreover, the core matrisome of the external dECM negatively regulated intracellular gene expression. Versican (VCAN) and Asporin (ASPN) might be the key ECM proteins influencing bone regeneration.

CONCLUSIONS

Accumulation of the core matrisome during noninduction led to solidification and the inactivation of bone regeneration. Targeting the core matrisome might effectively avoid the drawbacks of noninduced dECM, providing novel strategies for developing highly bioactive stem cell-derived dECM.

Use of allograft bone matrix in clinical orthopedics

Clinical orthopedics continuously aims to improve methods for bone formation. Clinical applications where bone formation is necessary include critical long bone defects in orthopedic trauma or tumor patients. Though some biomaterials combined with autologous stem cells significantly improve bone repair, critical-size damages are still challenged with the suitable implantation of biomaterials and donor cell survival. Extracellular matrix (ECM) is the fundamental structure in tissues that can nest and nourish resident cells as well as support specific functions of the tissue type. ECM also plays a role in cell signaling to promote bone growth, healing and turnover. In the last decade, the use of bone-derived ECMs or ECM-similar biomaterials have been widely investigated, including decellularized and demineralized bone ECM. In this article, we reviewed the current productions and applications of decellularized and demineralized bone matrices. We also introduce the current study of whole limb decellularization and recellularization.

Preclinical Evaluation of Bioactive Small Intestinal Submucosa-PMMA Bone Cement for Vertebral Augmentation

In vertebroplasty and kyphoplasty, bioinert poly(methyl methacrylate) (PMMA) bone cement is a conventional filler employed for quick stabilization of osteoporotic vertebral compression fractures (OVCFs). However, because of the poor osteointegration, excessive stiffness, and high curing temperature of PMMA, the implant loosens, the adjacent vertebrae refracture, and thermal necrosis of the surrounding tissue occurs frequently. This investigation addressed these issues by incorporating the small intestinal submucosa (SIS) into PMMA (SIS-PMMA). In vitro analyses revealed that this new SIS-PMMA bone cement had improved porous structure, as well as reduced compressive modulus and polymerization temperature compared with the original PMMA. Furthermore, the handling properties of SIS-PMMA bone cement were not significantly different from PMMA. The in vitro effect of PMMA and SIS-PMMA was investigated on MC3T3-E1 cells via the Transwell insert model to mimic the clinical condition or directly by culturing cells on the bone cement samples. The results indicated that SIS addition substantially enhanced the proliferation and osteogenic differentiation of MC3T3-E1 cells. Additionally, the bone cement's biomechanical properties were also assessed in a decalcified goat vertebrae model with a compression fracture, which indicated the SIS-PMMA had markedly increased compressive strength than PMMA. Furthermore, it was proved that the novel bone cement had good biosafety and efficacy based on the International Standards and guidelines. After 12 weeks of implantation, SIS-PMMA indicated significantly more osteointegration and new bone formation ability than PMMA. In addition, vertebral bodies with cement were also extracted for the uniaxial compression test, and it was revealed that compared with the PMMA-implanted vertebrae, the SIS-PMMA-implanted vertebrae had greatly enhanced maximum strength. Overall, these findings indicate the potential of SIS to induce efficient fixation between the modified cement surface and the host bone, thereby providing evidence that the SIS-PMMA bone cement is a promising filler for clinical vertebral augmentation.

Distinguished biomimetic dECM system facilitates early detection of metastatic breast cancer cells

Breast cancer is the most prevalent malignant tumor affecting women's health. Bone is the most common distant metastatic organ, worsening the quality of life and increasing the mortality of patients. Early detection of breast cancer bone metastasis is urgent for halting disease progression and improving tumor prognosis. Recently, extracellular matrix (ECM) with biomimetic tissue niches opened a new avenue for tumor models in vitro. Here, we developed a biomimetic decellularized ECM (dECM) system to recapitulate bone niches at different situations, bone mimetic dECM from osteoblasts (BM-ECM) and bone tumor mimetic dECM from osteosarcoma cells (OS-ECM). The two kinds of dECMs exhibited distinct morphology, protein composition, and distribution. Interestingly, highly metastatic breast cancer cells tended to adhere and migrate on BM-ECM, while lowly metastatic breast cancer cells preferred the OS-ECM niche. Epithelial-to-mesenchymal transition was a potential mechanism to initiate the breast cancer cell migration on different biomimetic dECMs. Importantly, in the nude mice model, the dECM system captured metastatic breast cancer cells as early as 10 days after orthotopic transplantation in mammary gland pads, with higher signal on BM-ECM than that on OS-ECM. Collectively, the biomimetic dECM system might be a promising tumor model to distinguish the metastatic ability of breast cancer cells in vitro and to facilitate early detection of metastatic breast cancer cells in vivo, contributing to the diagnosis of breast cancer bone metastasis.

Bioactivity, Molecular Mechanism, and Targeted Delivery of Flavonoids for Bone Loss

Skeletal disabilities are a prominent burden on the present population with an increasing life span. Advances in osteopathy have provided various medical support for bone-related diseases, including pharmacological and prosthesis interventions. However, therapeutics and post-surgery complications are often reported due to side effects associated with modern-day therapies. Thus, therapies utilizing natural means with fewer toxic or other side effects are the key to acceptable interventions. Flavonoids constitute a class of bioactive compounds found in dietary supplements, and their pharmacological attributes have been well appreciated. Recently, flavonoids' role is gaining renowned interest for its effect on bone remodeling. A wide range of flavonoids has been found to play a pivotal role in the major bone signaling pathways, such as wingless-related integration site (Wnt)/β-catenin, bone morphogenetic protein (BMP)/transforming growth factor (TGF)-β, mitogen-activated protein kinase (MAPK), etc. However, the reduced bioavailability and the absorption of flavonoids are the major limitations inhibiting their use against bone-related complications. Recent utilization of nanotechnological approaches and other delivery methods (biomaterial scaffolds, micelles) to target and control release can enhance the absorption and bioavailability of flavonoids. Thus, we have tried to recapitulate the understanding of the role of flavonoids in regulating signaling mechanisms affecting bone remodeling and various delivery methods utilized to enhance their therapeutical potential in treating bone loss.

Advances in Organoid Culture Research

Organoids are powerful systems to facilitate the study of individuals' disorders and personalized treatments because they mimic the structural and functional characteristics of organs. However, the full potential of organoids in research has remained unrealized and the clinical applications have been limited. One of the reasons is organoids are most efficient grown in reconstituted extracellular matrix hydrogels from mouse-derived, whose poorly defined, batch-to-batch variability and immunogenicity. Another reason is that organoids lack host conditions. As a component of the tumor microenvironment, microbiota and metabolites can regulate the development and treatment in several human malignancies. Here, we introduce several engineering matrix materials and review recent advances in the coculture of organoids with microbiota and their metabolites. Finally, we discuss current trends and future possibilities to build more complex cocultures.

Preparation and Use of Decellularized Extracellular Matrix for Tissue Engineering

The multidisciplinary fields of tissue engineering and regenerative medicine have the potential to revolutionize the practise of medicine through the abilities to repair, regenerate, or replace tissues and organs with functional engineered constructs. To this end, tissue engineering combines scaffolding materials with cells and biologically active molecules into constructs with the appropriate structures and properties for tissue/organ regeneration, where scaffolding materials and biomolecules are the keys to mimic the native extracellular matrix (ECM). For this, one emerging way is to decellularize the native ECM into the materials suitable for, directly or in combination with other materials, creating functional constructs. Over the past decade, decellularized ECM (or dECM) has greatly facilitated the advance of tissue engineering and regenerative medicine, while being challenged in many ways. This article reviews the recent development of dECM for tissue engineering and regenerative medicine, with a focus on the preparation of dECM along with its influence on cell culture, the modification of dECM for use as a scaffolding material, and the novel techniques and emerging trends in processing dECM into functional constructs. We highlight the success of dECM and constructs in the in vitro, in vivo, and clinical applications and further identify the key issues and challenges involved, along with a discussion of future research directions.

Traditional Chinese medicine promotes bone regeneration in bone tissue engineering

Bone tissue engineering (BTE) is a promising method for the repair of difficult-to-heal bone tissue damage by providing three-dimensional structures for cell attachment, proliferation, and differentiation. Traditional Chinese medicine (TCM) has been introduced as an effective global medical program by the World Health Organization, comprising intricate components, and promoting bone regeneration by regulating multiple mechanisms and targets. This study outlines the potential therapeutic capabilities of TCM combined with BTE in bone regeneration. The effective active components promoting bone regeneration can be generally divided into flavonoids, alkaloids, glycosides, terpenoids, and polyphenols, among others. The chemical structures of the monomers, their sources, efficacy, and mechanisms are described. We summarize the use of compounds and medicinal parts of TCM to stimulate bone regeneration. Finally, the limitations and prospects of applying TCM in BTE are introduced, providing a direction for further development of novel and potential TCM.

BMSCs and Osteoblast-Engineered ECM Synergetically Promotes Osteogenesis and Angiogenesis in an Ectopic Bone Formation Model

Bone mesenchymal stem cells (BMSCs) have been extensively used in bone tissue engineering because of their potential to differentiate into multiple cells, secrete paracrine factors, and attenuate immune responses. Biomaterials are essential for the residence and activities of BMSCs after implantation in vivo. Recently, extracellular matrix (ECM) modification with a favorable regenerative microenvironment has been demonstrated to be a promising approach for cellular activities and bone regeneration. The aim of the present study was to evaluate the effects of BMSCs combined with cell-engineered ECM scaffolds on osteogenesis and angiogenesis in vivo. The ECM scaffolds were generated by osteoblasts on the small intestinal submucosa (SIS) under treatment with calcium (Ca)-enriched medium and icariin (Ic) after decellularization. In a mouse ectopic bone formation model, the SIS scaffolds were demonstrated to reduce the immune response, and lower the levels of immune cells compared with those in the sham group. Ca/Ic-ECM modification inhibited the degradation of the SIS scaffolds in vivo. The generated Ca/Ic-SIS scaffolds ectopically promoted osteogenesis according to the results of micro-CT and histological staining. Moreover, BMSCs on Ca/Ic-SIS further increased the bone volume percentage (BV/TV) and bone density. Moreover, angiogenesis was also enhanced by the Ca/Ic-SIS scaffolds, resulting in the highest levels of neovascularization according to the data ofCD31 staining. In conclusion, osteoblast-engineered ECM under directional induction is a promising strategy to modify biomaterials for osteogenesis and angiogenesis. BMSCs synergetically improve the properties of ECM constructs, which may contribute to the repair of large bone defects.

Osteoblast/fibroblast coculture derived bioactive ECM with unique matrisome profile facilitates bone regeneration

Extracellular matrix (ECM) with mimetic tissue niches was attractive to facilitate tissue regeneration in situ via recruitment of endogenous cells and stimulation of self-healing process. However, how to engineer the complicate tissue specific ECM with unique matrisome in vitro was a challenge of ECM-based biomaterials in tissue engineering and regenerative medicine. Here, we introduced coculture system to engineer bone mimetic ECM niche guided by cell-cell communication. In the cocultures, fibroblasts promoted osteogenic differentiation of osteoblasts via extracellular vesicles. The generated ECM (MN-ECM) displayed a unique appearance of morphology and biological components. The advantages of MN-ECM were demonstrated with promotion of multiple cellular behaviors (proliferation, adhesion and osteogenic mineralization) in vitro and bone regeneration in vivo. Moreover, proteomic analysis was used to clarify the molecular mechanism of MN-ECM, which revealed a specific matrisome signature. The present study provides a novel strategy to generate ECM with tissue mimetic niches via cell-cell communication in a coculture system, which forwards the development of tissue-bioactive ECM engineering along with deepening the understanding of ECM niches regulated by cells for bone tissue engineering.

Icariin-Functionalized Nanodiamonds to Enhance Osteogenic Capacity In Vitro

Nanodiamonds (NDs) have been used as drug delivery vehicles due to their low toxicity and biocompatibility. Recently, it has been reported that NDs have also osteogenic differentiation capacity. However, their capacity using NDs alone is not enough. To significantly improve their osteogenic activity, we developed icariin (ICA)-functionalized NDs (ICA-NDs) and evaluated whether ICA-NDs enhance their in vitro osteogenic capacity. Unmodified NDs and ICA-NDs showed nanosized particles that were spherical in shape. The ICA-NDs achieved a prolonged ICA release for up to 4 weeks. The osteogenic capacities of NDs, ICA (10 μg)-NDs, and ICA (50 μg)-NDs were demonstrated by alkaline phosphatase (ALP) activity; calcium content; and mRNA gene levels of osteogenic-related markers, including ALP, runt-related transcript factor 2 (RUNX2), collagen type I alpha 1 (COL1A1), and osteopontin (OPN). In vitro cell studies revealed that ICA (50 μg)-ND-treated MC3T3-E1 cells greatly increased osteogenic markers, including ALP, calcium content, and mRNA gene levels of osteogenic-related markers, including ALP, RUNX2, COL1A1, and OPN compared to ICA (10 μg)-NDs or ND-treated cells. These our data suggest that ICA-NDs can promote osteogenic capacity.

Recent Advances in Biomaterials for the Treatment of Bone Defects

Bone defects or fractures generally heal in the absence of major interventions due to the high regenerative capacity of bone tissue. However, in situations of severe/large bone defects, these orchestrated regeneration mechanisms are impaired. With advances in modern medicine, natural and synthetic bio-scaffolds from bioceramics and polymers that support bone growth have emerged and gained intense research interest. In particular, scaffolds that recapitulate the molecular cues of extracellular signals, particularly growth factors, offer potential as therapeutic bone biomaterials. The current challenges for these therapies include the ability to engineer materials that mimic the biological and mechanical properties of the real bone tissue matrix, whilst simultaneously supporting bone vascularization. In this review, we discuss the very recent innovative strategies in bone biomaterial technology, including those of endogenous biomaterials and cell/drug delivery systems that promote bone regeneration. We present our understanding of their current value and efficacy, and the future perspectives for bone regenerative medicine.

Investigating the In Vitro Osteogenic Properties of the Inclusion Nanocarrier of Icariin with Beta-Cyclodextrin-Alginate

In this study, we created an inclusion nanocarrier of icariin (ICA) and β-cyclodextrin-alginate conjugate (ICA/β-CD-ALG) and determined its in vitro osteogenic ability on MC3T3-E1 cells. The morphological shape of the prepared β-CD-ALG with or without ICA was nano-sized and round. The use of β-CD-ALG achieved a sustained ICA release for up to 7 days. In vitro studies found that ICA/β-CD-ALG had a greater potential in osteogenesis on MC3T3-E1 cells compared to β-CD-ALG by exhibiting both higher alkaline phosphatase levels and the amount of calcium deposits. Moreover, ICA/β-CD-ALG greatly increased the levels of osteogenesis markers including osteocalcin (OCN) and osteopontin (OPN). Our results suggest that ICA/β-CD-ALG plays a significant role in cellular osteogenic activity.

Surface modification of small intestine submucosa in tissue engineering

With the development of tissue engineering, the required biomaterials need to have the ability to promote cell adhesion and proliferation in vitro and in vivo. Especially, surface modification of the scaffold material has a great influence on biocompatibility and functionality of materials. The small intestine submucosa (SIS) is an extracellular matrix isolated from the submucosal layer of porcine jejunum, which has good tissue mechanical properties and regenerative activity, and is suitable for cell adhesion, proliferation and differentiation. In recent years, SIS is widely used in different areas of tissue reconstruction, such as blood vessels, bone, cartilage, bladder and ureter, etc. This paper discusses the main methods for surface modification of SIS to improve and optimize the performance of SIS bioscaffolds, including functional group bonding, protein adsorption, mineral coating, topography and formatting modification and drug combination. In addition, the reasonable combination of these methods also offers great improvement on SIS surface modification. This article makes a shallow review of the surface modification of SIS and its application in tissue engineering.

Icariin-loaded porous scaffolds for bone regeneration through the regulation of the coupling process of osteogenesis and osteoclastic activity

Objective

Icariin (IC) promotes osteogenic differentiation, and it may be a potential small molecule drug for local application in bone regeneration. Icariin-loaded hydroxyapatite/alginate (IC/HAA) porous composite scaffolds were designed in this study for the potential application of the sustainable release of icariin and subsequent bone regeneration.

Methods

An icariin-loaded hydroxyapatite/alginate porous composite scaffold was prepared and characterized by SEM and HPLC for morphology and release behavior, respectively. The mechanical properties, degradation in PBS and cytotoxicity on BMSCs were also evaluated by MTT assay, compression strength and calculation of weight remaining ratio, respectively. Rabbit BMSCs were cocultured with IC/HAA scaffolds, and ALP activity and Alizarin Red staining were performed to evaluate osteogenic differentiation induction. The mRNA and protein expression level of an osteogenic gene was detected by RT-PCR and Western blotting, respectively. In vivo animal models of critical bone defects in the radius of rabbit were used. Four and 12 weeks after the implantation of IC/HAA scaffolds in the bone defect, radiographic images of the radius were obtained and scored by using the Lane and Sandhu X-ray scoring system. Tissue samples were also evaluated using H&E and Masson staining, and an osteogenic gene and Wnt signaling pathway genes were detected.

Results

A hydroxyapatite/alginate (HAA) porous composite scaffold-loaded icariin was fabricated using a freeze-drying method. Our data indicated that the icariin was loaded in alginate scaffold without compromising the macro/microstructure or mechanical properties of the scaffold. Notably, the IC/HAA promoted the proliferation of rBMSCs without exerting cytotoxicity on rBMSCs. In vivo, rabbit radius bone defect experiments demonstrated that the IC/HAA scaffold exhibited better capacity for bone regeneration than HAA, and IC/HAA upregulated the relative expression levels of an osteogenic gene and the Wnt signaling pathway genes. Most notably, the IC/HAA scaffold also inhibited osteoclast activity in vivo.

Conclusion

Our data suggests a promising application for the use of HAA scaffolds to load icariin and promote bone regeneration in situ through mediation of the coupling processes of osteogenesis induction and osteoclast activity inhibition.

ECM coating modification generated by optimized decellularization process improves functional behavior of BMSCs

Bone mesenchymal stem cells (BMSCs) have been widely applied in tissue engineering and regenerative medicine. However, small number of BMSCs and loss of stem cell characteristics after expansion in vitro limited clinical use of BMSCs. In the present study, osteoblasts were cultured to lay down extracellular matrix (ECM) and then the cells were removed (decellularization) to generate ECM coating substrates. The decellularization process was optimized to maximally remove cells and cellular components, along with integrated ECM retained which was demonstrated to be beneficial for BMSCs expansion in vitro. After decellularization, only less than 2% of residual DNA and cellular proteins were detected in TFFF-ECM (decellularized by triton X-100 (T) and three freeze/thaw cycles (FFF)), which was much less than that in TN-ECM generated by traditional decellularization method (triton X-100 (T) and NH₄OH (N)). Meanwhile, ECM components and structure were preserved best after decellularization by TFFF method. More ECM proteins were detected, and structure proteins (fibronectin and collagen) exhibited as classic network fibers in TFFF-ECM. Functionally, all kinds of decellularized ECM (dECM) were demonstrated to promote BMSCs proliferation and osteogenic differentiation capacity, thus maintain the stemness of BMSCs. Importantly, cells cultured on TFFF-ECM grew faster than the cells on other kinds of dECM at early stage and TFFF-ECM was beneficial to preserve stemness of BMSCs with high expression of OCT4 and NANOG when cultured in vitro. Proteomic analysis showed the proteins in ECM functioned in multiple biological activities and signaling pathways, which contributed to stemness maintenance of BMSC. Thus, the mild decellularization process optimized in this study enhanced the effectiveness of dECM for BMSCs culture in vitro and maybe further applied to BMSCs based tissue repair.

Icariin induces the growth, migration and osteoblastic differentiation of human periodontal ligament fibroblasts by inhibiting Toll-like receptor 4 and NF-κB p65 phosphorylation

The proliferation, migration and differentiation capacities of human periodontal ligament fibroblasts (HPDLCs) are important for the treatment of periodontal diseases. The aim of the present study was to investigate whether icariin could promote these abilities in HPDLCs, and explore the cellular mechanisms therein. The results indicated that icarrin markedly blocked apoptosis, and increased the viability and migration of HPDLCs, particularly at the concentrations of 20 and 50 µM. In addition, icariin significantly promoted HPDLCs to synthesize extracellular matrix, which was reflected by the decreased expression of matrix matalloproteinase-1 and increased expression of tissue inhibitor of metalloproteinase-1. Furthermore, the levels of bone morphogenetic protein 2, collagen I, osteoprotegerin and alkaline phosphatase were markedly elevated by icariin, indicating that icariin was able to promote the osteogenic differentiation capability of HPDLCs. Icariin also inactivated the Toll-like receptor 4 (TLR)-4/nuclear factor (NF)-κB signaling pathway by suppressing the expression levels of TLR-4 and phosphorylated p65, and by blocking p65 nuclear translocation. These results suggested that icarrin increased the survival, migration and osteoblastic differentiation of HPDLCs by inhibiting the TLR-4/NF-κB signaling pathway.