Scaffolds For Tissue Engineering Research Articles

Piezocatalytically-induced controllable mineralization scaffold with bone-like microenvironment to achieve endogenous bone regeneration

Orderly hierarchical structure with balanced mechanical, chemical, and electrical properties is the basis of the natural bone microenvironment. Inspired by nature, we developed a piezocatalytically-induced controlled mineralization strategy using piezoelectric polymer poly-L-lactic acid (PLLA) fibers with ordered micro-nano structures to prepare biomimetic tissue engineering scaffolds with a bone-like microenvironment (pcm-PLLA), in which PLLA-mediated piezoelectric catalysis promoted the in-situ polymerization of dopamine and subsequently regulated the controllable growth of hydroxyapatite crystals on the fiber surface. PLLA fibers, as analogs of mineralized collagen fibers, were arranged in an oriented manner, and ultimately formed a bone-like interconnected pore structure; in addition, they also provided bone-like piezoelectric properties. The uniformly sized HA nanocrystals formed by controlled mineralization provided a bone-like mechanical strength and chemical environment. The pcm-PLLA scaffold could rapidly recruit endogenous stem cells, and promote their osteogenic differentiation by activating cell membrane calcium channels and PI3K signaling pathways through ultrasound-responsive piezoelectric signals. In addition, the scaffold also provided a suitable microenvironment to promote macrophage M2 polarization and angiogenesis, thereby enhancing bone regeneration in skull defects of rats. The proposed piezocatalytically-induced controllable mineralization strategy provides a new idea for the development of tissue engineering scaffolds that can be implemented for multimodal physical stimulation therapy.

Potential Application of Polysaccharide-based Aerogel Scaffolds for Bone Tissue Engineering

Potential Application of Polysaccharide-based Aerogel Scaffolds for Bone Tissue Engineering

Design of Biomimetic Porous Scaffolds for Bone Tissue Engineering

Design of Biomimetic Porous Scaffolds for Bone Tissue Engineering

Effect of hydroxyapatite and pulsed electromagnetic field on osteogenic differentiation of human stem cells seeded onto 3D‐printed polycaprolactone scaffolds for future bone graft transplantation

AbstractBone graft transplantation is a risky procedure mainly due to postoperative complications. Tissue engineering is an alternative to regenerating bone tissue by seeding mesenchymal stem cells into 3D scaffolds by osteoinductive signaling. Poly(ε‐caprolactone) (PCL) is one of the most used biopolymers for fabricating scaffolds for bone tissue engineering. PCL is enriched with hydroxyapatite (HA) to promote the production of the bone‐mineralized matrix. Moreover, the application of pulsed electromagnetic fields (PEMFs) on scaffolds loaded with HA can significantly benefit collagen and HA networks favoring the interaction between organic and mineral phases of bones. In this context, we investigated, for the first time, the effect exerted by a PEMF exposure on the osteogenic differentiation of human adipose stem cells (hASCs) seeded onto 3D printed PCL‐HA scaffolds and cultured in growth and osteogenic medium (OM). After 21 days of culture, the results showed excellent colonization of scaffolds and the deposition of extracellular matrix (ECM) secreted by hASCs. Immunofluorescence staining confirmed the deposition of collagen type I and osteopontin both on scaffolds. Gene expression analysis indicated that both HA crystal and PEMF treatment were able to trigger osteogenic differentiation, as documented by the increase of osteogenic markers. These results suggest that HA, osteogenic factors, and PEMFs converge on the same signaling pathways as there are no additive effects and no change in protein synthesis between scaffolds with HA or treated with PEMFs for cells cultured in OM. The proposed study lays the foundations for exploring new approaches in bone graft transplantation.

Gelatin- zirconium based metal-organic framework (MOF 801) nanocomposite scaffold for bone tissue engineering

Tissue engineering applications in bone defect treatment have shown promising outcomes over the past decade. In this context, taking advantage of bioactive scaffolds mimicking the intrinsic composition of bone has resulted in remarkable effects on bone regeneration. In this study, Zirconium-based metal-organic framework, known as MOF 801, was synthesized and incorporated into the gelatin matrix as an osteoconductive agent to fabricate a nanocomposite bone scaffold by freeze-drying method. Physical and chemical characteristics of MOF 801 and nanocomposite scaffolds were analyzed using FE-SEM, EDS, XRD, ICP and FTIR. Besides, the biological activity of the prepared scaffolds was evaluated by MTT, alizarin red staining, crystal violet staining, and ALP assays. Inclusion of MOF 801 NPs into the scaffolds resulted in enhancement of their compressive strength up to 15 ± 0.05 MPa. The nanocomposite samples containing MOF 801 NPs also exhibited favorable bioactive feature that was confirmed by their apatite-forming ability on their surfaces upon immersion in SBF solution. The Zr ion and fumarate release studies illustrated sustained release profiles from the gelatin matrix, leading to both antioxidant and anti-inflammatory properties. MTT assay results affirmed biocompatibility of scaffolds containing up to 5 % w/w MOF 801, besides the crystal violet assay exhibited proper cell confluency and adhesion. Eventually, Alizarin red and ALP activity assays revealed that an increment of MOF 801 could induce calcium mineralization and Alkaline Phosphatase enzyme production in MG-63 cells confirming the potential of prepared scaffolds for related bone tissue engineering applications.

Arabinoxylan-based psyllium seed hydrocolloid: Single-step aqueous extraction and use in tissue engineering

Biomacromolecules derived from natural sources offer superior biocompatibility, biodegradability, and water-holding capacity, which make them promising scaffolds for tissue engineering. Psyllium seed has gained attention in biomedical applications recently due to its gel-forming ability, which is provided by its polysaccharide-rich content consisting mostly of arabinoxylan. This study focuses on the extraction and gelation of Psyllium seed hydrocolloid (PSH) in a single-step water-based protocol, and scaffold fabrication using freeze-drying method. After characterization of the scaffold, including morphological, mechanical, swelling, and protein adsorption analyses, 3D cell culture studies were done using NIH-3 T3 fibroblast cells on PSH scaffold, and cell viability was assessed using Live/Dead and Alamar Blue assays. Starting from day 1, high cell viability was obtained, and it reached 90 % at the end of 15-day culture period. Cellular morphology on PSH scaffold was monitored via SEM analysis; cellular aggregates then spheroid formation were observed throughout the study. Collagen Type-I and F-actin expressions were followed by immunostaining revealing a 9- and 10-fold increase during long-term culture. Overall, a single-step and non-toxic protocol was developed for extraction and gelation of PSH. Obtained results unveiled that PSH scaffold provided a favorable 3D microenvironment for cells, holding promise for further tissue engineering applications.

3D printed Nanohydroxyapatite/Polyamide 66 scaffolds with balanced mechanical property and osteogenic ability for bone repair

The biomaterial requirements for bone tissue repair are extremely strict. It not only requires the biomaterial to have good biocompatibility and biological activity, but also requires sufficient mechanical strength. Polyamide 66 (PA66) and nano-hydroxyapatite (n-HA) have been widely investigated in bone tissue engineering scaffold, however, its composites require further research. In this study, the 3D printing technology was utilized to fabricate personalized n-HA/PA66 bone tissue scaffold. The mechanical properties of n-HA/PA66 composite can be adjusted by configuring different raw material components and applying different porosity. It was found that 50 % porosity n-HA/PA66 composite scaffold showed a uniform porous structure and a compressive strength of 33.9 MPa. The composite scaffold also exhibited excellent biological properties while improving mechanical properties, in vitro cell tests indicated that the 3D printed n-HA/PA66 composite scaffold promoted differentiation of bone marrow mesenchymal stem cells (BMSCs) into osteoblasts. In in vivo animal model proved that the scaffold promoted endogenous bone regeneration in rabbit patellar bone defects, with newly formed bone volume of 20.9 % after two months of implantation. This research proposed a 3D printed polyamide/nano-hydroxyapatite composite with balanced mechanical property and osteogenic ability for customized bone tissue repair, and it has promising application prospects.

Facile synthesis of mechanically robust and injectable tetra-polyethylene glycol/methacrylate chitosan double-network hydrogel cartilage repair

The development of advanced hydrogel scaffolds with good biocompatibility, mechanical strength and bioactive property is highly desirable in cell growth, proliferation, and differentiation for the cartilage tissue regeneration. Herein, we reported a simple, inexpensive, feasible, and environmentally benign strategy to synthesize a biocompatible polyethylene glycol-based methacrylate-modified chitosan (PCSMA) double network (DN) hydrogel via the reversible Schiff base reaction and successive photopolymerization between the tetra-poly (ethylene glycol) aldehyde (Tetra-PEG-CHO) and methacrylate-modified chitosan (CSMA) in mild conditions. The four-terminated CHO groups were hypothesized to not only construct the whole architectural network through the dynamic pH-responsive Schiff base but also contribute to the injectable behavior and good tissue adhesion, which may furnish the surgeon with the availability of injectable and shapeless ability to fill in the gaps. Compared to the single PCS hydrogel with the main similar components of the tetra-PEG-CHO and pure CS moieties, the post-fabrication of PCSMA DN hydrogel possessed slower degradation time, denser network, and stronger mechanical stability, which could facilitate the bone marrow mesenchymal stem cell (BMSCs) activity and promote the chondrogenic differentiation for facilitating cartilage regeneration. Our study highlights the positive effects on chondrogenic performance and supports the PCSMA hydrogel as a promising tissue-engineered scaffold for the cartilage defect repair.

Enhanced contrast imaging with polyamide 6/Fe(OH)3 nanofibrous scaffolds: A focus on high T1 relaxivity

Nanofibers serve as widely employed tissue engineering scaffolds in diverse biomedical applications. When implanted in vivo, it is crucial for tissue engineering scaffolds to be visualizable, enabling the monitoring of their shape, position, and performance. This capability facilitates the effective assessment of implant deformations, displacements, degradations, and functionalities. However, in many biomedical imaging techniques such as magnetic resonance imaging (MRI), the contrast of tissue engineering scaffolds is often inadequate. MRI is particularly notable for its effectiveness in imaging soft tissues. Previous endeavors to enhance the contrast of tissue engineering scaffolds in MRI have involved the use of negative contrast agents (CAs). Nonetheless, negative CAs can result in artifacts, thus favoring the preference for positive CAs due to their ability to generate clearer boundaries. In this study, we successfully prepared composite polyamide 6 nanofibrous scaffolds with ultrafine dispersion Fe(OH)3 nanoparticles using electrospinning and in-situ growth techniques. The relaxation properties of the magnetic nanofibrous scaffolds confirmed the successful production of scaffolds suitable for positive imaging. In vitro cell seeding experiments demonstrated the efficient proliferation and adhesion of endothelial cells and fibroblasts. In vivo studies further revealed the biocompatibility and functionality of the scaffolds. These findings indicate that the prepared PA6/Fe(OH)3 composite nanofibrous scaffolds can enable straightforward, safe, and efficient in vivo positive contrast MRI monitoring, thereby playing a pivotal role in the integration of diagnosis and treatment within tissue engineering scaffolds.

Anticancer and Antibacterial Evaluation of Pure Poly(o-Toluidine) for Tissue Engineering and Cancer Treatment

Chemical oxidative polymerization was employed to synthesize pure poly (ortho-toluidine) (POT). The synthesized POT was characterized using XRD, FT-IR, and SEM analyses. Additionally, the samples were subjected to biological evaluation. The antibacterial activity of POT was tested against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria. Notably, E. coli displayed significant susceptibility to POT's antibacterial effects, especially at higher concentrations. Furthermore, in vitro anticancer experiments were conducted on MG-63 bone cancer cells to assess the cytotoxicity of POT. Pristine POT exhibited the highest level of cytotoxicity, as evidenced by an IC50 value of 83.15 g/ml. In summary, this investigation highlights the robust antibacterial and anticancer activities of POT. These findings suggest potential applications of POT in areas such as tissue engineering scaffolds, anticancer therapies, and various biomedical uses.

3D cotton-type anisotropic biomimetic scaffold with low fiber motion electrospun via a sharply inclined array collector for induced osteogenesis

Electrospinning is an effective method to fabricate fibrous scaffolds that mimic the ECM of bone tissue on a nano- to macro-scale. However, a limitation of electrospun fibrous scaffolds for bone tissue engineering is the structure formed by densely compacted fibers, which significantly impedes cell infiltration and tissue ingrowth. To address this problem, several researchers have developed numerous techniques for fabricating 3D fibrous scaffolds with customized topography and pore size. Despite the success in developing various 3D electrospun scaffolds based on fiber repulsion, the lack of contact points between fibers in those scaffolds has been shown to hinder cell attachment, migration, proliferation, and differentiation due to excessive movement of the fibers. In this article, we introduce a Dianthus caryophyllus-inspired scaffold fabricated using SIAC-PE, a modified collector under specific viscosity conditions of PCL/LA solution. The developed scaffold mimicking the structural similarities of the nature-inspired design presented enhanced cell proliferation, infiltration, and increased expression of bone-related factors by reducing fiber movements, presenting high space interconnection, high porosity, and controlled fiber topography.

Brain neurotrophic factor BDNF: new data, functions and questions

The brain-derived neurotrophic factor (BDNF) is a key modulator of neurogenesis, synaptogenesis, neuroregeneration, and cell differentiation in the nervous system. Impaired BDNF functioning is a characteristic of various neurological diseases, such as Alzheimer’s disease, multiple sclerosis, and depressive disorders. There is recent evidence that patients with COVID-19 have reduced BDNF levels in the blood plasma. Furthermore, exogenous BDNF and its mimetics have demonstrated therapeutic potential.
 In this review, we systematized data of the BDNF gene structure, epigenetic and microRNA-mediated regulation of its expression, transcriptional variants of BDNF, and the effects of BDNF on neuronal and oligodendroglial differentiation. Further, we point out the gaps in the current knowledge about BDNF and propose experiments that can expand such knowledge and the range of possibilities for using BDNF in biomedicine. These include determining the expression pattern of all BDNF gene transcripts at different stages of differentiation and in different cell subpopulations and studying the role of receptor-independent BDNF signaling, circadian fluctuations in BDNF levels, and their role in physiological and pathophysiological conditions. Finally, for translational medicine, evaluating the effect of BDNF mimetics (including those immobilized on three-dimensional scaffolds for tissue engineering) on neuronal and oligodendroglial differentiation of pluripotent and polypotent cells and identifying molecular regulators of BDNF transcription, including small molecules and microRNAs capable of regulating BDNF gene expression, are crucial.

From common biomass materials to high-performance tissue engineering scaffold: Biomimetic preparation, properties characterization, in vitro and in vivo evaluations

Converting common biomass materials to high-performance biomedical products could not only reduce the environmental pressure associated with the large-scale use of synthetic materials, but also increase the economic value. Chitosan as a very promising candidate has drawn considerable attention owing to its abundant sources and remarkable bioactivities. However, pure chitosan materials usually exhibit insufficient mechanical properties and excessive swelling ratio, which seriously affected their in vivo stability and integrity when applied as tissue engineering scaffolds. Thus, simultaneously improving the mechanical strength and biological compatibility of pure chitosan (CS) scaffolds becomes very important. Here, inspired by the fiber-reinforced construction of natural extracellular matrix and the porous structure of cancellous bone, we built silk microfibers/chitosan composite scaffolds via ice-templating technique. This biomimetic strategy achieved 500% of mechanical improvement to pure chitosan, and meanwhile still maintaining high porosity (> 87%). In addition, the increased roughness of chitosan pore walls by embedded silk microfibers significantly promoted cell adhesion and proliferation. More importantly, after subcutaneous implantation in mice for four weeks, the composite scaffold showed greater structural integrity, as well as better collagenation, angiogenesis, and osteogenesis abilities, suggesting its great potential in biomedicine.

Understanding Matrix Stiffness in Vinyl Polymer Hydrogels: Implications in Bone Tissue Engineering.

Matrix elasticity helps to direct bone cell differentiation, impact healing processes, and modify extracellular matrix deposition, all of which are required for tissue growth and maintenance. In this work, we evaluated the role of inorganic nanocrystals or mineral inducers such as nanohydroxyapatite, alkaline phosphatase, and nanoclay also known as montmorillonite deposited on vinyl-based hydrogels in generating matrices with different stiffness and their role in cell differentiation. Poly-2-(dimethylamino)ethyl methacrylate (PD) and poly-2-hydroxypropylmethacrylamide (PH) are the two types of vinyl polymers chosen for preparing hydrogels via thermal cross-linking. The hydrogels exhibited porosity, which decreased with an increase in stiffness. Each of the compositions is non-cytotoxic and maintains the viability of pre-osteoblasts (MC3T3-E1) and human bone marrow mesenchymal stem cells (hBMSCs). The PD hydrogels in the presence of ALP showed the highest mineralization ability confirmed through the alizarin assay and a better structural environment for their use as scaffolds for tissue engineering. The study reveals that understanding such interactions can generate hydrogels that can serve as efficient 3D models to study biomineralization.

Structure and function of engineered stromal cell-derived factor-1α.

To design biologically active, collagen-based scaffolds for bone tissue engineering, we have synthesized chimeric proteins consisting of stromal cell-derived factor-1α (SDF) and the von Willebrand factor A3 collagen-binding domain (CBD). The chimeric proteins were used to evaluate the effect of domain linkage and its order on the structure and function of the SDF and CBD. The structure of the chimeric proteins was analyzed by circular dichroism spectroscopy, while functional analysis was performed by a cell migration assay for the SDF domain and a collagen-binding assay for the CBD domain. Furthermore, computational structural prediction was conducted for the chimeric proteins to examine the consistency with the results of structural and functional analyses. Our structural and functional analyses as well as structural prediction revealed that linking two domains can affect their functions. However, their order had minor effects on the three-dimensional structure of CBD and SDF in the chimeric proteins.

Polyhydroxybutyrate-based osteoinductive mineralized electrospun structures that mimic components and tissue interfaces of the osteon for bone tissue engineering.

Scaffolds for bone tissue engineering should enable regeneration of bone tissues with its native hierarchically organized ECM and multiple tissue interfaces. To achieve this, inspired by the structure and properties of bone osteon, we fabricated polyhydroxybutyrate-based mineralized electrospun fibrous scaffolds. After studying multiple polyhydroxybutyrate (PHB)-based fibers, we chose 7%PHB/1%Gelatin fibers (PG) to fabricate mineralized fibers that mimic mineralized collagen fibers in bone. The mineralized PG (mPG) surface had a rough, hydrophilic layer of low crystalline calcium phosphate which was biocompatible to BMSCs, induced their proliferation and was osteoinductive. Subsequently, by modulating the electrospinning process, we fabricated mPG-based novel higher order fibrous scaffolds that mimic the macroscale geometries of osteons of bone ECM. Inspired by the aligned collagen fibers in bone lamellae, we fabricated mPG scaffolds with aligned fibers that could direct anisotropic elongation of mBMSCs. Further, we fabricated electrospun mPG-based osteoinductive tubular constructs which can mimic cylindrical bone components like osteons or lamellae or be used as long bone analogues based on their dimensions. Finally, to regenerate tissue interfaces in bone, we introduced a novel bi-layered scaffold-based approach. An electrospun bi-layered tubular construct that had PG in the outer layer and 7%PHB/0.5%Polypyrrole fibers (PPy) in the inner layer was fabricated. The bi-layered tubular construct underwent preferential surface mineralization only on its outer layer. This outer mineralized layer supported osteogenesis while the inner PPy layer could support neural cell growth. Thus, the bi-layered tubular construct may be used to regenerate haversian canal in the osteons which hosts nerve fibers. Overall, the study introduced novel techniques to fabricate biomimetic structures that can regenerate components of bone osteon and its multiple tissue interfaces. The study lays foundation for the fabrication of a modular scaffold that can regenerate bone with its hierarchical structure and complex tissue interfaces.

A novel, microfluidic high-throughput single-cell encapsulation of human bone marrow mesenchymal stromal cells

The efficacy of stem-cell therapy depends on the ability of the transplanted cells to escape early immunological reactions and to be retained at the site of transplantation. The use of tissue engineering scaffolds or injectable biomaterials as carriers has been proposed, but they still present limitations linked to a reliable manufacturing process, surgical practice and clinical outcomes. Alginate microbeads are potential candidates for the encapsulation of mesenchymal stromal cells with the aim of providing a delivery carrier suitable for minimally-invasive and scaffold-free transplantation, tissue-adhesive properties and protection from the immune response. However, the formation of stable microbeads relies on the cross-linking of alginate with divalent calcium ions at concentrations that are toxic for the cells, making control over the beads’ size and a single-cell encapsulation unreliable. The present work demonstrates the efficiency of an innovative, high throughput, and reproducible microfluidic system to produce single-cell, calcium-free alginate coatings of human mesenchymal stromal cells. Among the various conditions tested, visible light and confocal microscopy following staining of the cell nuclei by DAPI showed that the microfluidic system yielded an optimal single-cell encapsulation of 2000 cells/min in 2% w/v alginate microcapsules of reproducible morphology and an average size of 28.2 ± 3.7 µm. The adhesive properties of the alginate microcapsules, the viability of the encapsulated cells and their ability to escape the alginate microcapsule were demonstrated by the relatively rapid adherence of the beads onto tissue culture plastic and the cells’ ability to gradually disrupt the microcapsule shell after 24 h and proliferate. To mimic the early inflammatory response upon transplantation, the encapsulated cells were exposed to proliferating macrophages at different cell seeding densities for up to 2 days and the protection effect of the microcapsule on the cells assessed by time-lapse microscopy showing a shielding effect for up to 48 h. This work underscores the potential of microfluidic systems to precisely encapsulate cells by good manufacturing practice standards while favouring cell retention on substrates, viability and proliferation upon transplantation.Graphical

Synthesis and characterization of a magnetic bacterial cellulose-chitosan nanocomposite and evaluation of its applicability for osteogenesis

Introduction: Natural biopolymers are used for various purposes in healthcare, such as tissue engineering, drug delivery, and wound healing. Bacterial cellulose and chitosan were preferred in this study due to their non-cytotoxic, biodegradable, biocompatible, and non-inflammatory properties. The study reports the development of a magnetic bacterial cellulose-chitosan (BC-CS-Fe3O4) nanocomposite that can be used as a biocompatible scaffold for tissue engineering. Iron oxide nanoparticles were included in the composite to provide superparamagnetic properties that are useful in a variety of applications, including osteogenic differentiation, magnetic imaging, drug delivery, and thermal induction for cancer treatment. Methods: The magnetic nanocomposite was prepared by immersing Fe3O4 in a mixture of bacterial cellulose-chitosan scaffold and then freeze-drying it. The resulting nanocomposite was characterized using FE-SEM and FTIR techniques. The swelling ratio and mechanical strength of the scaffolds were evaluated experimentally. The biodegradability of the scaffolds was assessed using PBS for 8 weeks at 37°C. The cytotoxicity and osteogenic differentiation of the nanocomposite were studied using human adipose-derived mesenchymal stem cells (ADSCs) and alizarin red staining. One-way ANOVA with Tukey's multiple comparisons test was used for statistical analysis. Results: The FTIR spectra demonstrated the formation of bonds between functional groups of nanoparticles. FE-SEM images showed the integrity of the fibrillar network. The magnetic nanocomposite has the highest swelling ratio (2445% ± 23.34) and tensile strength (5.08 MPa). After 8 weeks, the biodegradation ratios of BC, BC-CS, and BC-CS-Fe3O4 scaffolds were 0.75% ± 0.35, 2.5% ± 0.1, and 9.5% ± 0.7, respectively. Magnetic nanocomposites have low toxicity (P < 0.0001) and higher osteogenic potential compared to other scaffolds. Conclusion: Based on its high tensile strength, low water absorption, suitable degradability, low cytotoxicity, and high ability to induce an increase in calcium deposits by stem cells, the magnetic BC-CS-Fe3O4 nanocomposite scaffold can be a suitable candidate as a biomaterial for osteogenic differentiation.

Properties of Carbonated Hydroxyapatite-Based Scaffold from Oyster Shells Composited with Honeycomb and Polyethylene Oxide for Bone Tissue Engineering Applications

Scaffold Carbonated Hydroxyapatite/Honeycomb/Polyethylene Oxide (CHA/HCB/PEO) has been obtained by freeze-drying. The bioceramic CHA used in this study was synthesized from oyster shells using precipitation. HCB and PEO were added as reinforcement materials that affect the crystallographic properties of the scaffold. This study aimed to determine the characteristics of the scaffolds for bone tissue engineering. CHA and scaffolds were characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffractometer (XRD), and Scanning Electron Microscopy (SEM). FTIR spectra and XRD graphs confirmed that the CHA produced was B-type. FTIR spectra of the scaffold showed the presence of HCB and PEO in the scaffold, which means they were homogeneously bound in the scaffold solution. XRD test results show that scaffolds' crystallinity and crystallite size tends to decrease compared to CHA. This was good because they could make cells easier to proliferate. A small-scale pore structure (micropore) was also formed in the scaffold. The porosity and pore size of the scaffold were affected by the concentration of CHA. The presence of the micropores can increase the permeability of the scaffold and facilitate cell migration. Thus, the composition of CHA/HCB/PEO scaffolds can be a good candidate material in bone tissue engineering.

Biomimetic multilayer scaffolds with prolonged retention of stem cells-recruiting and angiogenic peptides for promoting bladder regeneration

The complications of enterocystoplasy have challenged traditional bladder reconstruction methods. Tissue engineering scaffolds, involving stem cells implantation and vascularization strategies, emerge as promising alternatives. However, their applications are hindered by issues regarding the source of stem cells and the rapid loss of bioactive factors in a urinary environment. Here, a multilayer biomimetic scaffold consisting of polycaprolactone (PCL) nanofibrous mats and oxidized dextran/carboxymethyl chitosan hydrogel has been synthesized. Bone marrow homing peptide (BMHP) and vascular endothelial growth factor-mimicking peptide (VP) were incorporated into the hydrogel to recruit endogenous stem cells and promote vascularization, respectively. The results indicated that PCL mats not only reinforced the mechanical properties of composite scaffolds but also prolonged the retention of peptides via the hydrophobic surface. In vivo experiments demonstrated that BMHP and VP had crosstalk effects, amplifying their functions to accelerate bladder regeneration, enhance contractility of smooth muscle cells, inhibit fibrosis, and improve innervation. Overall, the novel functionalized scaffolds are potentially viable for urologic tissue reconstruction.