3D Scaffolds Research Articles

Emerging Bioprinting for Wound Healing.

Bioprinting has attracted much attention due to its suitability for fabricating biomedical devices. In particular, bioprinting has become one of the growing centers in the field of wound healing, with various types of bioprinted devices being developed, including 3D scaffolds, microneedle patches, and flexible electronics. Bioprinted devices can be designed with specific biostructures and biofunctions that closely match the shape of wound sites and accelerate the regeneration of skin through various approaches. Herein, a comprehensive review of the bioprinting of smart wound dressings is presented, emphasizing the crucial effect of bioprinting in determining biostructures and biofunctions. The review begins with an overview of bioprinting techniques and bioprinted devices, followed with an in-depth discussion of polymer-based inks, modification strategies, additive ingredients, properties, and applications. The strategies for the modification of bioprinted devices are divided into seven categories, including chemical synthesis of novel inks, physical blending, coaxial bioprinting, multimaterial bioprinting, physical absorption, chemical immobilization, and hybridization with living cells, and examples are presented. Thereafter, the frontiers of bioprinting and wound healing, including 4D bioprinting, artificial intelligence-assisted bioprinting, and in situ bioprinting, are discussed from a perspective of interdisciplinary sciences. Finally, the current challenges and future prospects in this field are highlighted.

The effect of nodal connectivity and strut density within stochastic titanium scaffolds on osteogenesis.

Modern orthopaedic implants use lattice structures that act as 3D scaffolds to enhance bone growth into and around implants. Stochastic scaffolds are of particular interest as they mimic the architecture of trabecular bone and can combine isotropic properties and adjustable structure. The existing research mainly concentrates on controlling the mechanical and biological performance of periodic lattices by adjusting pore size and shape. Still, less is known on how we can control the performance of stochastic lattices through their design parameters: nodal connectivity, strut density and strut thickness. To elucidate this, four lattice structures were evaluated with varied strut densities and connectivity, hence different local geometry and mechanical properties: low apparent modulus, high apparent modulus, and two with near-identical modulus. Pre-osteoblast murine cells were seeded on scaffolds and cultured in vitro for 28days. Cell adhesion, proliferation and differentiation were evaluated. Additionally, the expression levels of key osteogenic biomarkers were used to assess the effect of each design parameter on the quality of newly formed tissue. The main finding was that increasing connectivity increased the rate of osteoblast maturation, tissue formation and mineralisation. In detail, doubling the connectivity, over fixed strut density, increased collagen type-I by 140%, increased osteopontin by 130% and osteocalcin by 110%. This was attributed to the increased number of acute angles formed by the numerous connected struts, which facilitated the organization of cells and accelerated the cell cycle. Overall, increasing connectivity and adjusting strut density is a novel technique to design stochastic structures which combine a broad range of biomimetic properties and rapid ossification.

Combination techniques towards novel drug delivery systems manufacturing: 3D PCL scaffolds enriched with tetracycline-loaded PVP nanoparticles

Drug delivery systems based on synthetic and natural polymers offer a new approach with a capacity to control the release of bio-active agents within time. In this work, we present different designs of Polycaprolactone (PCL) 3D scaffolds containing Polyvinylpyrrolidone (PVP) nanoparticles that can store a hydrophilic drug. The drug delivery system, combined of PCL and PVP polymers fabricated by additive manufacturing, aims for a solution for longer and more stabled drug delivery carrier. The drug, planned to be released to the targeted area, is sprayed with the electrospray method inside PVP nanoparticles on the different layers of the fabricated PCL scaffolds 3D printing. This makes obtaining a layered and porous scaffold and drug-loaded nanoparticles within this structure easier. Obtained PCL scaffolds containing Tetracyclines (Tet) loaded PVP nanoparticles showed that drug encapsulation into the interlayer extended the release time and exhibited a controlled release profile for days. Moreover, produced scaffolds have good biocompatibility and no harmful effects. The combination of 3D scaffolds and drug-loaded nanoparticles aims to develop new functional scaffolds by targeting more efficient and longer-lasting drug delivery.

Bioinspired 3D microprinted cell scaffolds: Integration of graph theory to recapitulate complex network wiring in lymph nodes.

Physical networks are ubiquitous in nature, but many of them possess a complex organizational structure that is difficult to recapitulate in artificial systems. This is especially the case in biomedical and tissue engineering, where the microstructural details of 3D cell scaffolds are important. Studies of biological networks-such as fibroblastic reticular cell (FRC) networks-have revealed the crucial role of network topology in a range of biological functions. However, cell scaffolds are rarely analyzed, or designed, using graph theory. To understand how networks affect adhered cells, 3D culture platforms capturing the complex topological properties of biologically relevant networks would be needed. In this work, we took inspiration from the small-world organization (high clustering and low path length) of FRC networks to design cell scaffolds. An algorithmic toolset was created to generate the networks and process them to improve their 3D printability. We employed tools from graph theory to show that the networks were small-world (omega factor, ω =-0.10±0.02; small-world propensity, SWP=0.74±0.01). 3D microprinting was employed to physicalize networks as scaffolds, which supported the survival of FRCs. This work, therefore, represents a bioinspired, graph theory-driven approach to control the networks of microscale cell niches.

Fabrication of magnetic nanocomposite scaffolds based on polyvinyl alcohol-chitosan containing hydroxyapatite and clay modified with graphene oxide: Evaluation of their properties for bone tissue engineering applications

One of the most common systems for bone tissue engineering is polymeric scaffolds. However, the low mechanical properties of polymeric scaffolds, considering the properties required for bone replacement tissue, are the main challenge for researchers in this field. For bone tissue engineering, this research prepared nanocomposite scaffolds based on polyvinyl alcohol-chitosan containing modified clay and hydroxyapatite (HAp). HAp used in these 3D scaffolds was synthesized from a chicken femur, and Cloisite 30B clay nanoparticles were modified by graphene oxide and Fe3O4 nanoparticles to strengthen their mechanical properties. Sample characteristics were determined using FT-IR, XRD, SEM, TGA, swelling rate, laboratory degradation, and biological and mechanical properties. These analyses showed that 2% of modified clay (C30B/GO/Fe3O4, CGF) inside the nanocomposite scaffold increased the compressive strength 23 times compared to the pristine polymer scaffold. Also, adding HAp particles and modified clay simultaneously increased the mineralization on the surface of the scaffolds. Final nanocomposite scaffolds were found to have a compressive strength of 9.31 MPa, a porosity of 75 %, and a porosity size of 50 nm and were in the range of cancellous bone. The final swelling amount is 1790 %, which is the amount that is Favorable for bone scaffold. Finally, the analysis results to determine the samples' toxicity showed that none of the prepared scaffolds were toxic and showed good cell viability.

Micro-Vessels-Like 3D Scaffolds for Studying the Proton Radiobiology of Glioblastoma-Endothelial Cells Co-Culture Models.

Glioblastoma (GBM) is a devastating cancer of the brain with an extremely poor prognosis. While X-ray radiotherapy and chemotherapy remain the current standard, proton beam therapy is an appealing alternative as protons can damage cancer cells while sparing the surrounding healthy tissue. However, the effects of protons on in vitro GBM models at the cellular level, especially when co-cultured with endothelial cells, the building blocks of brain micro-vessels, are still unexplored. In this work, novel 3D-engineered scaffolds inspired by the geometry of brain microvasculature are designed, where GBM cells cluster and proliferate. The architectures are fabricated by two-photon polymerization (2PP), pre-cultured with endothelial cells (HUVECs), and then cultured with a human GBM cell line (U251). The micro-vessel structures enable GBM in vivo-like morphologies, and the results show a higher DNA double-strand breakage in GBM monoculture samples when compared to the U251/HUVECs co-culture, with cells in 2D featuring a larger number of DNA damage foci when compared to cells in 3D. The discrepancy in terms of proton radiation response indicates a difference in the radioresistance of the GBM cells mediated by the presence of HUVECs and the possible induction of stemness features that contribute to radioresistance and improved DNA repair.

Copper and Cobalt Nanoparticles Enable Highly Stable and Fast Kinetics of Al–S Batteries

AbstractAluminum–Sulfur (Al–S) batteries are regarded as promising energy storage devices due to their high energy‐to‐price ratios and safety. However, they suffer from clumsy S ↔ Al2S3 reactions and short lifespans that limit their practical application. By combining the merits of adsorptive Cu, catalytic Co, and conductive N‐doped carbon matrix, the bimetals decorated N‐doped carbon (Cu1Co1@NC) enables smooth adsorption and conversion of polysulfides. Consequently, the S@Cu1Co1@NC exhibits excellent electrochemical performance (delivering a high capacity of 317.5 mAh g−1 after 320 cycles at 1.5 A g−1). Moreover, the Cu‐endowed strong Al affinity and robust 3D scaffold with Co‐enhanced conductivity can regulate Al3+ depositing/stripping and successfully suppress Al dendrites. As a result, the Cu1Co1@NC displays negligible Al nucleation overpotential and provides ultra‐long lifespan (>10 000 h) and exceptional reversible (Coulombic efficiency = 99.8–99.9%) Al3+ plating/stripping. Integrating all these advantages, a full Al–S cell constructed with Cu1Co1@NC as two‐in‐one hosts demonstrates excellent capacity retention with enhanced reversibility. This work provides insights into the design of promising Al–S batteries based on bifunctional CuCo bimetal and favorable 3D framework.

Functionalization of poly (lactic-co-glycolic acid) nano‑calcium sulphate and fucoidan 3D scaffold using human bone marrow mesenchymal stromal cells for bone tissue engineering application

This study aimed to functionalize a novel porous PLGA (Poly lactic-co-glycolic acid) composite scaffold in combination with nano‑calcium sulphate (nCS) and/or fucoidan (FU) to induce osteogenic differentiation of human bone marrow stromal cells. The composite scaffolds (PLGA-nCS-FU, PLGA-nCS or PLGA-FU) were fabricated and subjected to characterization using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) and Energy Dispersive X-Ray (EDX). The biocompatibility and osteogenic induction potential of scaffolds on seeded human bone marrow derived mesenchymal stromal cells (hBMSCs) were studied using cell attachment and alamar blue cell viability and alkaline phosphatase (ALP), osteocalcin and osteogenic gene expression, respectively. The composition of different groups was reflected in FTIR, XRD and EDX. The SEM micrographs revealed a difference in the surface of the scaffold before and after FU addition. The confocal imaging and SEM micrographs confirmed the attachment of cells onto all three composite scaffolds. However, the AB assay indicated a significant increase (p < 0.05) in cell viability/proliferation seeded on PLGA-nCS-FU on day 21 and 28 as compared with other combinations. A 2-fold significant increase (p < 0.05) in ALP and OC secretion of seeded hBMSCs onto PLGA-nCS-FU was observed when compared with other combinations. A significant increase in RUNX2, OPN, COL-I and ALP genes were observed in the cells seeded on PLGA-nCS-FU on day 14 and 28 as compared with day 0. In conclusion, the incorporation of both Fucoidan and Nano‑calcium sulphate with PLGA showed a promising improvement in the osteogenic potential of hBMSCs. Therefore, PLGA-nCS-FU could be the ideal candidate for subsequent pre-clinical studies to develop a successful bone substitute to repair critical bone defects.

Biomimicking 3D soft scaffold combined with electrical stimulation to manipulate neural stem cell differentiation for guidance spinal cord injury repair

Spinal cord injury repair has remained a challenging issue in the medical field, and in recent years neural stem cell-based therapies have shown great potential. However, the survival and controlled differentiation of neural stem cells (NSCs) remain a problem, since the majority of materials can’t provide a suitable microenvironment for NSCs. In this work, we design and develop a conductive hydrogel mimicking spinal cord tissue as a biomimetic 3D biomaterial soft scaffold to improve the survival microenvironment and regulate the differentiation direction of NSCs. Significantly, the designed hydrogel matches the spinal cord tissue in aspects of mechanical properties, electrical conductivity, and pore structure. Moreover, the hydrogel possesses injectability, self-healing and haemostatic properties. Combining hydrogel with electrical stimulation (ES) induces loaded NSCs to be more inclined toward neuronal differentiation, axonal growth, and myelin regeneration, while reducing astrocyte development. This treatment strategy will ultimately achieve spinal cord injury repair and motor function restoration while avoiding glial scar deposition. This mimicking spinal cord 3D soft scaffolds combined with ES provide a promising therapeutic strategy for spinal cord injury repair.

Production of a Bioink Containing Decellularized Spinal Cord Tissue for 3D Bioprinting.

For the past few years, three-dimensional (3D) bioprinting has emerged as a promising approach in the field of regenerative medicine. This technique allows for the production of 3D scaffolds to support cell transplantation due to its ability to mimic the extracellular environment. One alternative to enhancing cell adhesion, survival, and proliferation is the use of decellularized extracellular matrix as a bioink component. The aim of this study was to produce a bioink using lyophilized rat decellularized spinal cord tissue (DSCT) for 3D bioprinting of nervous tissue. DNA quantification, hematoxylin and eosin and DAPI staining indicated that 1% sodium dodecyl sulfate and 9 h processing were effective in removing the cells from the spinal cord samples. The cell viability assay showed that the decellularized matrix is not cytotoxic for PC12 cells. The hydrogel containing DSCT, alginate, and gelatine used as the base for the bioink has a shear thinning behavior and low G″/G' ratio, allowing for good printability without compromising cell viability after 3D bioprinting. The bioink supported long-term PC12 cell survival, with 93% of live cells 4 weeks after printing, and stimulated the production of laminin-1 and neurofilament-M. This bioink, therefore, represents an easily available biomaterial for central nervous system tissue engineering.

Three-dimensional glass scaffolds improve the In Vitro maturation of porcine cumulus-oocyte complexes and subsequent embryonic development after parthenogenetic activation

In vitro maturation (IVM) methods for porcine oocytes are still deficient in achieving full developmental capacity, as the currently available oocyte in vitro culture systems still have limitations. In vitro embryo production must also improve the porcine oocyte IVM system to acquire oocytes with good developmental potential. Herein, we tested a three-dimensional (3D) glass scaffold culture system for porcine oocyte maturation. After 42 h, we matured porcine cumulus-oocyte complexes (COCs) on either two-dimensional glass dishes (2D-B), two-dimensional microdrops (2D-W), or 3D glass scaffolds. The 3D glass scaffolds were tested for porcine oocyte maturation and embryonic development. Among these culture methods, the extended morphology of the 3D group maintained a 3D structure better than the 2D-B and 2D-W groups, which had flat COCs that grew close to the bottom of the culture vessel. The COCs of the 3D group had a higher cumulus expansion index and higher first polar body extrusion rate, cleavage rate, and blastocyst rate of parthenogenetic embryos than the 2D-B group. In the 3D group, the cumulus-expansion-related gene HAS2 and anti-apoptotic gene Bcl-2 were significantly upregulated (p < 0.05), while the pro-apoptotic gene Caspase3 was significantly downregulated (p < 0.05). The blastocysts of the 3D group had a higher relative expression of Bcl-2, Oct4, and Nanog than the other two groups (p < 0.05). The 3D group also had a more uniform distribution of mitochondrial membrane potential and mitochondria (p < 0.05), and its cytoplasmic active oxygen species content was much lower than that in the 2D-B group (p < 0.05). These results show that 3D glass scaffolds dramatically increased porcine oocyte maturation and embryonic development after parthenogenetic activation, providing a suitable culture model for porcine oocytes.

Digital light processing of customized elastic scaffolds by efficient thiol-yne crosslinking

Digital light processing (DLP) based 3D printing technology has the advantages of fast printing rate and high spatial resolution in the manufacture of tissue engineering scaffolds. However, the limited availability of printable materials for DLP technology, especially the lack of biodegradable elastomeric materials hinders the development of customized soft tissue scaffolds. Herein, liquid poly(4-methyl-ε-caprolactone) dialkynylate (PMCLDY) was prepared as a DLP printable ink based on efficient thiol-yne photocrosslinking. With the aid of photorheology and in situ FT-IR and tensile tests, an ink formulation for DLP printing was optimized as the P50 ink (PMCLDY to diluent PEGDY mass ratio of 1), which possessed fast cure rates (<15 s), low viscosity (<2 Pa·s), moderate mechanical properties (failure strain > 40 %) and maximum toughness (0.153 MJ·m−3). A commercial DLP printer equipped with the P50 ink realized 3D scaffolds models with microstructure and macroscopic shape precisely. It was demonstrated that the 3D printed scaffold with biodegradability could withstand dynamic compression cycles. Furthermore, the cytocompatibility experiments showed that the scaffold could effectively support the growth and proliferation of rat bone marrow stromal cells (BMSCs). These results demonstrate that the P50 ink is a promising material for manufacturing elastic scaffolds by DLP printing for tissue engineering applications.

3D printing viscoelastic hydrogel-based scaffolds with a swelling-dependent gate for cartilage injury regeneration

Regeneration of articular cartilage remains a great challenge due to its poor self-healing capacity and weak stability. The microfracture surgery (MF) can provide bone marrow mesenchymal stem cells (BMSCs) and is commonly used in clinical practice, but its therapeutic effect is still limited by the lack of effective adhesion matrix and the uncontrollable tendency to develop fibrosis and even mineralization. In this study, a small molecular drug-loaded viscoelastic hydrogel-based 3D printing bilayer scaffold with a swelling-dependent gate was successfully developed to address these limitations. The scaffold consisted of a lower layer with a smaller pore size and an upper matrix with larger pore size. The former acted as a swelling-dependent gate to switch pore size, which initially was on-state allowing the infiltration of BMSCs, and eventually transformed into off-state serving as a barrier blocking excessive blood support from the bone marrow after swelling-induced closure of pores. This barrier structure cooperated with fatty acid inhibitor-suppressed hypertrophy of neo-cartilage matrix. The latter provided a biocompatible and viscoelastic matrix to guide MSCs toward stable chondrogenic commitment. By integrating structural design with the inhibitor, the bilayer scaffold provides a promising platform for future clinical applications of MF surgery in cartilage regeneration.

Creation of a 3D Goethite-Spongin Composite Using an Extreme Biomimetics Approach.

The structural biopolymer spongin in the form of a 3D scaffold resembles in shape and size numerous species of industrially useful marine keratosan demosponges. Due to the large-scale aquaculture of these sponges worldwide, it represents a unique renewable source of biological material, which has already been successfully applied in biomedicine and bioinspired materials science. In the present study, spongin from the demosponge Hippospongia communis was used as a microporous template for the development of a new 3D composite containing goethite [α-FeO(OH)]. For this purpose, an extreme biomimetic technique using iron powder, crystalline iodine, and fibrous spongin was applied under laboratory conditions for the first time. The product was characterized using SEM and digital light microscopy, infrared and Raman spectroscopy, XRD, thermogravimetry (TG/DTG), and confocal micro X-ray fluorescence spectroscopy (CMXRF). A potential application of the obtained goethite-spongin composite in the electrochemical sensing of dopamine (DA) in human urine samples was investigated, with satisfactory recoveries (96% to 116%) being obtained.

Stretchable Sponge-Based Electrochemical Biosensor for Real-Time Sensing of Cells in Three-Dimensional Culture.

For the study of cell biology, real-time information on cell physiological processes will be more accurate and closer to the in vivo condition in a three-dimensional (3D) culture system. Although most reported 3D cell culture scaffolds can better mimic the in vivo dynamic microenvironment, the real-time analysis technique is deficient or lacking. Herein, a stretchable and conductive 3D scaffold is developed to construct an electrochemical biosensor for real-time monitoring of cell release in 3D culture under stimulation of drug stimulant and mechanical force. In our design, the polyurethane sponge (PU) dipped with conductive carbon ink (CC/PU) was used as a conductive scaffold, and gold nanoparticles (nano-Au) were electrodeposited on the CC/PU (nano-Au CC/PU) to improve the electrochemical sensing performance. The prepared nano-Au CC/PU scaffold exhibits a good electrocatalytic ability to H2O2 with a linear range from 20 nM to 43 μM. Due to the great biocompatibility, HeLa cells can be cultured directly on the nano-Au CC/PU and the in situ and real-time tracking of H2O2 secretion from cells was achieved. The results demonstrate that both the drug stimulant and mechanical force can rapidly activate the release of reactive oxygen species. This study indicates that the stretchable 3D sensing scaffold has good potential for cell biology research in an in vivo-like microenvironment and can be extensively used in the fields of tissue engineering, drug screening, and pathological research.

Three-Dimensional Printer-Assisted Electrospinning for Fabricating Intricate Biological Tissue Mimics.

Although regenerative medicine necessitates advanced three-dimensional (3D) scaffolds for organ and tissue applications, creating intricate structures across scales, from nano- to meso-like biological tissues, remains a challenge. Electrospinning of nanofibers offers promise due to its capacity to craft not only the dimensions and surfaces of individual fibers but also intricate attributes, such as anisotropy and porosity, across various materials. In this study, we used a 3D printer to design a mold with polylactic acid for gel modeling. This gel template, which was mounted on a metal wire, facilitated microfiber electrospinning. After spinning, these structures were treated with EDTA to remove the template and were then cleansed and dried, resulting in 3D microfibrous (3DMF) structures, with average fiber diameters of approximately 1 µm on the outer and inner surfaces. Notably, these structures matched their intended design dimensions without distortion or shrinkage, demonstrating the adaptability of this method for various template sizes. The cylindrical structures showed high elasticity and stretchability with an elastic modulus of 6.23 MPa. Furthermore, our method successfully mimicked complex biological tissue structures, such as the inner architecture of the voice box and the hollow partitioned structure of the heart's tricuspid valve. Achieving specific intricate shapes required multiple spinning sessions and subsequent assemblies. In essence, our approach holds potential for crafting artificial organs and forming the foundational materials for cell culture scaffolds, addressing the challenges of crafting intricate multiscale structures.

Short-term exposure to TNF-α promotes odontogenesis of stem cells of apical papilla on nanofibrous poly(l-lactic acid) scaffolds

The aim of this study was to investigate the effect of short-term (3 days) preconditioning with pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) on proliferation and odontogenic differentiation of stem cells of apical papilla (SCAP) seeded on a 3D scaffold. Our results showed that while TNF-α preconditioning at various concentrations did not affect SCAP proliferation, it enhanced alkaline phosphatase (ALP) activity and mineralized matrix deposition in culture. Preconditioning SCAP using TNF-α at a concentration of about 1 ng/ml optimally enhanced odontogenic gene expression of SCAP in culture. Highly porous nanofibrous (NF) poly(l-lactic acid) (PLLA) scaffolds, with nanofiber features mimicking the environment of the extracellular matrix, were fabricated using a thermally induced phase separation method. TNF-α preconditioning of SCAP at 1 ng/ml promoted ALP activity, calcium deposition and mineralized tissue formation of SCAP cultured on 3D NF-PLLA scaffolds in vitro. Moreover, TNF-α preconditioning at a concentration of 1 ng/ml promoted the formation of more mineralized tissue as well as stronger DSPP expression of SCAP seeded on NF-PLLA scaffolds in vivo. Collectively, this study suggests that short term TNF-α preconditioning, mimicking the transiently low concentration TNF-α present during inflammation, may serve as a feasible approach to enhance the odontogenic differentiation of stem/progenitor cells on a biomimetic scaffold for 3D dentin regeneration. These results present a first step in the development of a dental tissue engineering strategy where odontogenesis is enhanced by modulating inflammation.

Cross‐Linking Strategies for Silk‐Protein‐Based Inks for 3D Printing

AbstractDue to excellent biocompatibility, sufficient raw material, robust mechanical properties and easy cross‐linking, Silk Fibroin (SF) is a promising protein for 3D printing inks and an ideal candidate for 3D scaffolds in fields like regenerative medicine, bioelectronics and bio‐optics. In order to meet the requirements of print accuracy, mechanical properties and form retention capabilities, the first step is to prepare SF 3D printing inks using physical, chemical or other strategies of cross‐linking. The basic chemical groups and physical structure of SF determines its ability to form 3D networks under different conditions using various cross‐linking strategies. In the preparation of SF‐based 3D printing inks, physical, chemical or other strategies of cross‐linking improve the qualities of printing, but each strategy has its advantages and disadvantages. This paper discusses different crosslinking strategies for SF to support the development of exciting potential for SF‐based 3D printing inks to meet more needs in the future.

Gelatin scaffold ameliorates proliferation & stem cell differentiation into the hepatic like cell and support liver regeneration in partial-hepatectomized mice model

Stem cell-based tissue engineering is an emerging tool for developing functional tissues of choice. To understand pluripotency and hepatic differentiation of mouse embryonic stem cells (mESCs) on a three-dimensional (3D) scaffold, we established an efficient approach for generating hepatocyte-like cells (HLCs) from hepatoblast cells. We developed porous and biodegradable scaffold, which was stimulated with exogenous growth factors and investigated stemness and differentiation capacity of mESCs into HLCs on the scaffold in-vitro. In animal studies, we had cultured mESCs-derived hepatoblast-like cells on the scaffold and then, transplanted them into the partially hepatectomized C57BL/6 male mice model to evaluate the effect of gelatin scaffold on hepatic regeneration. The 3D culture system allowed maintenance of stemness properties in mESCs. The step-wise induction of mESCs with differentiation factors leads to the formation of HLCs and expressed liver-specific genes, including albumin, hepatocyte nucleic factor 4 alpha, and cytokeratin 18. In addition, cells also expressed Ki67, indicating cells are proliferating. The secretome showed expression of albumin, urea, creatinine, alanine transaminase, and aspartate aminotransferase. However, the volume of the excised liver which aids regeneration has not been studied. Our results indicate that hepatoblast cells on the scaffold implanted in PH mouse indicates that these cells efficiently differentiate into HLCs and cholangiocytes, forming hepatic lobules with central and portal veins, and bile duct-like structures with neovascularization. The gelatin scaffold provides an efficient microenvironment for liver differentiation and regeneration both in-vitro and in-vivo. These hepatoblasts cells would be a valuable source for 3D liver tissue engineering/transplantation in liver diseases.

A silk fibroin scaffold that accelerates both biodegradation and cell proliferation by incorporating sericin

When 3D silk fibroin scaffolds are used for the regeneration of soft tissues with fast regeneration rates, such as skin dermis, one concern is to accelerate the biodegradation of scaffolds and to match the degradation rate of scaffolds with the regeneration rate of tissues. In this study, sericin was incorporated into 3D silk fibroin scaffolds through crosslinking and followed by freeze-drying. The effects of incorporating sericin on the pore wall microstructure within the scaffolds, the biodegradability of scaffolds and cell proliferation within scaffolds were investigated. It was found that a large number of secondary pores and nanoscale particles were generated on the pore walls within the scaffolds due to the incorporation of sericin and that the number of secondary pores and the size of the particles increased with increasing sericin proportion. The results of in vitro biodegradation and coculture with human umbilical vein vascular endothelial cells demonstrated that the incorporation of sericin not only significantly accelerated the degradation of 3D silk fibroin scaffolds, but also promoted cell adhesion and proliferation. The secondary pores and particles generated on the pore walls inside the fibroin/sericin hybrid scaffolds had a positive contribution to promoting cell adhesion and proliferation. This study provides a biocompatible method for the modification of silk fibroin scaffolds, which can not only accelerate the biodegradation of the scaffold but also promote the adhesion and proliferation of seeded cells.