Temperature-responsive hydroxybutyl chitosan for the culture of mesenchymal stem cells and intervertebral disk cells

Revolutionizing pressure ulcer regeneration: Unleashing the potential of extracellular matrix-derived temperature-sensitive injectable antioxidant hydrogel for superior stem cell therapy

Pressure ulcers are a common issue in elderly and medically compromised individuals, posing significant challenges in healthcare. Human umbilical cord mesenchymal stem cells (HUMSCs) offer therapeutic benefits like inflammation modulation and tissue regeneration, yet challenges in cell survival, retention, and implantation rates limit their clinical application. Hydrogels in three-dimensional (3D) stem cell culture mimic the microenvironment, improving cell survival and therapeutic efficacy. A thermosensitive injectable hydrogel (adEHG) combining gallic acid-modified hydroxybutyl chitosan (HBC-GA) with soluble extracellular matrix (adECM) has been developed to address these challenges. The hybrid hydrogel, with favorable physical and chemical properties, shields stem cells from oxidative stress and boosts their therapeutic potential by clearing ROS. The adEHG hydrogel promotes angiogenesis, cell proliferation, and collagen deposition, further enhancing inflammation modulation and wound healing through the sustained release of therapeutic factors and cells. Additionally, the adEHG@HUMSC composite induces macrophage polarization towards an M2 phenotype, which is crucial for wound inflammation inhibition and successful healing. Our research significantly propels the field of stem cell-based therapies for pressure ulcer treatment and underscores the potential of the adEHG hydrogel as a valuable tool in advancing regenerative medicine.

Crocin-1 laden thermosensitive chitosan-based hydrogel with smart anti-inflammatory performance for severe full-thickness burn wound therapeutics

Burns are the fourth most common type of civilian trauma worldwide, and the management of severe irregular scald wounds remains a significant challenge. Herein, crocin-1 laden hydroxybutyl chitosan (CRO-HBC) thermosensitive hydrogel with smart anti-inflammatory performance was developed for accelerating full-thickness burn healing. The injectable and shape adaptability of the CRO-HBC gel make it a promising candidate for effectively filling scald wounds with irregular shapes, while simultaneously providing protection against external pathogens. The CRO-HBC gel network formed by hydrophobic interactions exhibited an initial burst release of crocin-1, followed by a gradual and sustained release over time. The excessive release of ROS and pro-inflammatory cytokines should be effectively regulated in the early stage of wound healing. The controlled release of crocin-1 from the CRO-HBC gel adequately addresses this requirement for wound healing. The CRO-HBC hydrogel also exhibited an excellent biocompatibility, an appropriate biodegradability, keratinocyte migration facilitation properties, and a reactive oxygen species scavenging capability. The composite CRO-HBC hydrogel intelligently mitigated inflammatory responses, promoted angiogenesis, and exhibited a commendable efficacy for tissue regeneration in a full-thickness scalding model. Overall, this innovative temperature-sensitive CRO-HBC injectable hydrogel dressing with smart anti-inflammatory performance has enormous potential for managing severe scald wounds.

Temperature-sensitive injectable chitosan-based hydrogel for endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) is an effective treatment for polyps and early gastrointestinal cancers, but requires a high level of operator skill. Injecting submucosal materials (SIM) helps create a fluid cushion between the mucosal and muscular layers, making the procedure easier and reducing associated risks. However, SIMs commonly used in current clinical practice tend to spread quickly and fail to provide long-lasting submucosal fluid cushions (SFC). Thus, there is a critical need for a material that is easy to inject while also maintaining a durable barrier. We prepared succinylated hydroxybutyl chitosan (HBC-SA) by adding succinic anhydride (SA) to hydroxybutyl chitosan (HBC). The hydrogel had excellent temperature-sensitive properties and was able to be injected via an endoscopic injection needle even after gel formation. In vitro and in vivo studies showed that it has satisfactory biocompatibility. Functional experiments showed that the submucosal lifting properties of this hydrogel were significantly better than that of normal saline (NS) and sodium hyaluronate (SH), two commonly used clinical materials. In addition, the hydrogel possessed excellent hemostatic properties. Based on these results, HBC-SA is a promising candidate for submucosal injection during ESD.

Emulsion stability of hydroxybutyl chitosan as emulsifier at low pH: Effects of the degree of substitutions of hydroxybutyl groups

Keeping the stability of emulsions at low pH is necessary for their successful applications in food and delivery systems. To achieve this goal, hydroxybutyl chitosan (HBC) with three degrees of substitution (DSs) was used as an emulsifier to investigate the effect of HBC structure on the emulsion stability. The DSs of HBC-5, HBC-10, and HBC-20 were 0.66, 1.51, and 2.19, respectively. The stability of oil-in-water emulsions against creaming/coalescence was positively correlated with the DS. As pH decreased to 2, HBC-20-stabilized emulsions were most stable without creaming or coalescence. After 30 days of storage, no changes in the droplet sizes of HBC-20-stabilized emulsions were observed, whereas the droplet sizes of HBC-5/10- stabilized emulsions significantly increased at low pH. The stability of HBC-20- stabilized emulsions at low pH was attributed to the higher surface activity and electrostatic repulsion. Our research revealed that the emulsion stability of HBC under low pH conditions can be controlled by the density of the hydroxybutyl groups in HBC. In vitro digestion further revealed the excellent stability of HBC-20-stabilized emulsions in simulated gastric fluid, which highlighted the enormous potential of HBC-20 to protect liposoluble drugs and nutrients from the extreme pH environment.

Thermo-Responsive Hydrogels Coupled with Photothermal Agents for Biomedical Applications

Intelligent hydrogels are materials with abilities to change their chemical nature or physical structure in response to external stimuli showing promising potential in multitudinous applications. Especially, photo-thermo coupled responsive hydrogels that are prepared by encapsulating photothermal agents into thermo-responsive hydrogel matrix exhibit more attractive advantages in biomedical applications owing to their spatiotemporal control and precise therapy. This work summarizes the latest progress of the photo-thermo coupled responsive hydrogel in biomedical applications. Three major elements of the photo-thermo coupled responsive hydrogel, i.e., thermo-responsive hydrogel matrix, photothermal agents, and construction methods are introduced. Furthermore, the recent developments of these hydrogels for biomedical applications are described with some selected examples. Finally, the challenges and future perspectives for photo-thermo coupled responsive hydrogels are outlined.

Hydrogels with Reversible Crosslinks for Improved Localised Stem Cell Retention: A Review

Successful stem cell applications could have a significant impact on the medical field, where many lives are at stake. However, the translation of stem cells to the clinic could be improved by overcoming challenges in stem cell transplantation and in vivo retention at the site of tissue damage. This review aims to showcase the most recent insights into developing hydrogels that can deliver, retain, and accommodate stem cells for tissue repair. Hydrogels can be used for tissue engineering, as their flexibility and water content makes them excellent substitutes for the native extracellular matrix. Moreover, the mechanical properties of hydrogels are highly tuneable, and recognition moieties to control cell behaviour and fate can quickly be introduced. This review covers the parameters necessary for the physicochemical design of adaptable hydrogels, the variety of (bio)materials that can be used in such hydrogels, their application in stem cell delivery and some recently developed chemistries for reversible crosslinking. Implementing physical and dynamic covalent chemistry has resulted in adaptable hydrogels that can mimic the dynamic nature of the extracellular matrix.

Coaxial 3D printing of hierarchical structured hydrogel scaffolds for on-demand repair of spinal cord injury

After spinal cord injury (SCI), endogenous neural stem cells (NSCs) near the damaged site are activated, but few NSCs migrate to the injury epicenter and differentiate into neurons because of the harsh microenvironment. It has demonstrated that implantation of hydrogel scaffold loaded with multiple cues can enhance the function of endogenous NSCs. However, programming different cues on request remains a great challenge. Herein, a time-programmed linear hierarchical structure scaffold is developed for spinal cord injury recovery. The scaffold is obtained through coaxial 3D printing by encapsulating a dual-network hydrogel (composed of hyaluronic acid derivatives and N-cadherin modified sodium alginate, inner layer) into a temperature responsive gelatin/cellulose nanofiber hydrogel (Gel/CNF, outer layer). The reactive species scavenger, metalloporphyrin, loaded in the outer layer is released rapidly by the degradation of Gel/CNF, inhibiting the initial oxidative stress at lesion site to protect endogenous NSCs; while the inner hydrogel with appropriate mechanical support, linear topology structure and bioactive cues facilitates the migration and neuronal differentiation of NSCs at the later stage of SCI treatment, thereby promoting motor functional restorations in SCI rats. This study offers an innovative strategy for fabrication of multifunctional nerve regeneration scaffold, which has potential for clinical treatment of SCI. STATEMENT OF SIGNIFICANCE: Two major challenges facing the recovery from spinal cord injury (SCI) are the low viability of endogenous neural stem cells (NSCs) within the damaged microenvironment, as well as the difficulty of neuronal regeneration at the injured site. To address these issues, a spinal cord-like coaxial scaffold was fabricated with free radical scavenging agent metalloporphyrin Mn (III) tetrakis (4-benzoic acid) porphyrin and chemokine N-cadherin. The scaffold was constructed by 3D bioprinting for time-programmed protection and modulation of NSCs to effectively repair SCI. This 3D coaxially bioprinted biomimetic construct enables multi-factor on-demand repair and may be a promising therapeutic strategy for SCI.

Investigations into the effects of scaffold microstructure on slow-release system with bioactive factors for bone repair

In recent years, bone tissue engineering (BTE) has played an essential role in the repair of bone tissue defects. Although bioactive factors as one component of BTE have great potential to effectively promote cell differentiation and bone regeneration, they are usually not used alone due to their short effective half-lives, high concentrations, etc. The release rate of bioactive factors could be controlled by loading them into scaffolds, and the scaffold microstructure has been shown to significantly influence release rates of bioactive factors. Therefore, this review attempted to investigate how the scaffold microstructure affected the release rate of bioactive factors, in which the variables included pore size, pore shape and porosity. The loading nature and the releasing mechanism of bioactive factors were also summarized. The main conclusions were achieved as follows: i) The pore shapes in the scaffold may have had no apparent effect on the release of bioactive factors but significantly affected mechanical properties of the scaffolds; ii) The pore size of about 400 μm in the scaffold may be more conducive to controlling the release of bioactive factors to promote bone formation; iii) The porosity of scaffolds may be positively correlated with the release rate, and the porosity of 70%-80% may be better to control the release rate. This review indicates that a slow-release system with proper scaffold microstructure control could be a tremendous inspiration for developing new treatment strategies for bone disease. It is anticipated to eventually be developed into clinical applications to tackle treatment-related issues effectively.

Chitosan-based hydrogel wound dressing: From mechanism to applications, a review

As promising biomaterials, hydrogels are widely used in the medical engineering field, especially in wound repairing. Compared with traditional wound dressings, such as gauze and bandage, hydrogel could absorb and retain more water without dissolving or losing its three-dimensional structure, thus avoiding secondary injury and promoting wound healing. Chitosan and its derivatives have become hot research topics for hydrogel wound dressing production due to their unique molecular structure and diverse biological activities. In this review, the mechanism of wound healing was introduced systematically. The mechanism of action of chitosan in the first three stages of wound repair (hemostasis, antimicrobial properties and progranulation), the effect of chitosan deacetylation and the molecular weight on its performance are analyzed. Additionally, the recent progress in intelligent and drug-loaded chitosan-based hydrogels and the features and advantages of chitosan were discussed. Finally, the challenges and prospects for the future development of chitosan-based hydrogels were discussed.

Proliferative and Osteogenic Supportive Effect of VEGF-Loaded Collagen-Chitosan Hydrogel System in Bone Marrow Derived Mesenchymal Stem Cells

The use of hydrogel (HG) in regenerative medicine is an emerging field and thus several approaches have been proposed recently to find an appropriate hydrogel system. In this sense, this study developed a novel HG system using collagen, chitosan, and VEGF composites for culturing mesenchymal stem cells (MSCs), and investigated their ability for osteogenic differentiation and mineral deposition. Our results showed that the HG loaded with 100 ng/mL VEGF (HG-100) significantly supported the proliferation of undifferentiated MSCs, the fibrillary filament structure (HE stain), mineralization (alizarin red S and von Kossa stain), alkaline phosphatase, and the osteogenesis of differentiated MSCs compared to other hydrogels (loaded with 25 and 50 ng/mL VEGF) and control (without hydrogel). HG-100 showed a higher VEGF releasing rate from day 3 to day 7 than other HGs, which substantially supports the proliferative and osteogenic properties of HG-100. However, the HGs did not increase the cell growth in differentiated MSCs on days 14 and 21 due to the confluence state (reach stationary phase) and cell loading ability, regardless of the VEGF content. Similarly, the HGs alone did not stimulate the osteogenesis of MSCs; however, they increased the osteogenic ability of MSCs in presence of osteogenic supplements. Accordingly, a fabricated HG with VEGF could be used as an appropriate system to culture stem cells for bone and dental regeneration.

Construction of adhesive and bioactive silk fibroin hydrogel for treatment of spinal cord injury

Spinal cord injury (SCI) often causes severe and permanent disabilities due to the complexity of injury progression. The promising methods are generally based on tissue engineering technology using biocompatible hydrogels to achieve SCI repair. However, hydrogels are commonly incapable of close contact with the damaged spinal cord stumps and fail to support neural regeneration in SCI. Therefore, it is still a challenge to achieve stable contact with the transected nerve stumps and accelerate neural regeneration in the lesion microenvironment. Here, an in situ forming glycidyl methacrylated silk fibroin/ laminin-acrylate (SF-GMA/LM-AC) hydrogel was fabricated for SCI repair. The polymer chains formed a network quickly after ultraviolet (UV)-light trigger, in topological entanglement with the spinal cord, stitching the hydrogel and wet tissues together like a suture at the molecular scale. The SF-GMA/LM-AC hydrogel also provided a favorable environment for the growth of cells due to the incorporation of LM-AC. Compared with physical entrapment of LM, LM-AC immobilized in the hydrogel by covalent technology provided better microenvironments for neural stem cells (NSCs) growth. The repair of complete transection SCI in rats demonstrated that this hydrogel guided and promoted neural regeneration over 8 weeks, leading to hind limb locomotion recovery. This adhesive and bioactive SF-GMA/LM-AC hydrogel may open many opportunities in various therapeutic indications, including SCI. STATEMENT OF SIGNIFICANCE: Many materials have been developed for building transplanted scaffolds, but it is still a challenge to fabricate bioactive scaffolds and adhesion to wet tissues. In this study, we successfully developed an in situ forming SF-GMA/LM-AC hydrogel for SCI repair. This in situ forming hydrogel formed significant adhesion to the native spinal cord, stitching hydrogel and tissue together like a suture at the molecular scale. In addition, covalent immobilized LM-AC was used as the contact guidance biochemical cues for axonal outgrowth and had much better bioactive effects than physically entangled LM. Moreover, this universal strategy would open an avenue to fabricate adhesive and bioactive hydrogel for various disease treatments including SCI.

Role of Hydrophobic Associations in Self-Healing Hydrogels Based on Amphiphilic Polysaccharides

Self-healing hydrogels have the ability to recover their original properties after the action of an external stress, due to presence in their structure of reversible chemical or physical cross-links. The physical cross-links lead to supramolecular hydrogels stabilized by hydrogen bonds, hydrophobic associations, electrostatic interactions, or host-guest interactions. Hydrophobic associations of amphiphilic polymers can provide self-healing hydrogels with good mechanical properties, and can also add more functionalities to these hydrogels by creating hydrophobic microdomains inside the hydrogels. This review highlights the main general advantages brought by hydrophobic associations in the design of self-healing hydrogels, with a focus on hydrogels based on biocompatible and biodegradable amphiphilic polysaccharides.

Thermosensitive and biodegradable PCL-based hydrogels: potential scaffolds for cartilage tissue engineering

Due to a lack of sufficient blood supply and unique physicochemical properties, the treatment of injured cartilage is laborious and needs an efficient strategy. Unfortunately, most of the current therapeutic approaches are, but not completely, unable to restore the function of injured cartilage. Tissue engineering-based modalities are an alternative option to reconstruct the injured tissue. Considering the unique structure and consistency of cartilage tissue (osteochondral junction), it is mandatory to apply distinct biomaterials with unique properties slightly different from scaffolds used for soft tissues. PCL is extensively used for the fabrication of fine therapeutic scaffolds to accelerate the restorative process. Thermosensitive PCL hydrogels with distinct chemical compositions have paved the way for sophisticated cartilage regeneration. This review aimed to collect recent findings regarding the application of PCL in hydrogels blended with natural, synthetic materials in the context of cartilage healing.

Generation of dorsoventral human spinal cord organoids via functionalizing composite scaffold for drug testing

The spinal cord possesses highly complex, finely organized cytoarchitecture guided by two dorsoventral morphogenic organizing centers. Thus, generation of human spinal cord tissue in vitro is challenging. Here, we demonstrated a novel method for generation of human dorsoventral spinal cord organoids using composite scaffolds. Specifically, the spinal cord ventralizing signaling Shh agonist (SAG) was loaded into a porous chitosan microsphere (PCSM), then thermosensitive Matrigel was coated on the surface to form composite microspheres with functional sustained-release SAG, termed as PCSM-Matrigel@SAG. Using PCSM-Matrigel@SAG as the core to induce 3D engineering of human spinal cord organoids from human pluripotent stem cells (ehSC-organoids), we found ehSC-organoids could form dorsoventral spinal cord-like cytoarchitecture with major domain-specific progenitors and neurons. Besides, these ehSC-organoids also showed functional calcium activity. In summary, these ehSC-organoids are of great significance for modeling spinal cord development, drug screening as 3D models for motor neuron diseases, and spinal cord injury repair.

Application of Nano-Inspired Scaffolds-Based Biopolymer Hydrogel for Bone and Periodontal Tissue Regeneration

This review's objectives are to provide an overview of the various kinds of biopolymer hydrogels that are currently used for bone tissue and periodontal tissue regeneration, to list the advantages and disadvantages of using them, to assess how well they might be used for nanoscale fabrication and biofunctionalization, and to describe their production processes and processes for functionalization with active biomolecules. They are applied in conjunction with other materials (such as microparticles (MPs) and nanoparticles (NPs)) and other novel techniques to replicate physiological bone generation more faithfully. Enhancing the biocompatibility of hydrogels created from blends of natural and synthetic biopolymers can result in the creation of the best scaffold match to the extracellular matrix (ECM) for bone and periodontal tissue regeneration. Additionally, adding various nanoparticles can increase the scaffold hydrogel stability and provide a number of biological effects. In this review, the research study of polysaccharide hydrogel as a scaffold will be critical in creating valuable materials for effective bone tissue regeneration, with a future impact predicted in repairing bone defects.

Release of O-GlcNAc transferase inhibitor promotes neuronal differentiation of neural stem cells in 3D bioprinted supramolecular hydrogel scaffold for spinal cord injury repair

Precise fabrication of biomimetic three-dimensional (3D) structure and effective neuronal differentiation under the pathological environment are the key to neural stem cell (NSC)-based spinal cord injury (SCI) therapy. In this study, we have developed a spinal cord-like bioprinted scaffold loading with OSMI-4, a small molecule O-GlcNAc transferase (OGT) inhibitor, to induce and guide the neuron differentiation of NSCs for efficient SCI repair. To achieve this, we developed a supramolecular bioink (SM bioink) consisting of methacrylated gelatin and acrylated β-cyclodextrins to load NSCs and OSMI-4. This bioink showed fast gelation and stable mechanical properties, facilitating bioprinting of functional neural scaffolds. Moreover, the weak host-guest cross-linking of the SM scaffolds significantly improved the cell-matrix interaction for the infiltration and migration of NSCs. What's more, the sustained delivery of OSMI-4 remarkably enhanced the intrinsic neuronal differentiation of the encapsulated NSCs in vitro by inhibiting Notch signaling pathway. In vivo experiment further revealed that the functional bioprinted scaffolds promoted the neuronal regeneration and axonal growth, leading to significant locomotor recovery of the SCI model rats. Together, the NSC-laden bioprinted SM scaffolds in combination with sustained release of the therapeutic agent OSMI-4 largely induced neuronal differentiation of NSCs and thus leading to efficient SCI repair. STATEMENT OF SIGNIFICANCE: Efficient neuronal differentiation of neural stem cells (NSCs) under the complex pathological microenvironment of spinal cord injury (SCI) is a major challenge of neural regeneration. By the use of a supramolecular bioink, we bioprinted a spinal cord-like scaffold loaded with NSCs and a small molecule drug OSMI-4 to significantly induce neuronal differentiation of NSCs for efficient SCI repair in vivo. The scaffolds with spinal cord-like structure can support the interaction and neuronal differentiation of NSCs by providing a dynamic matrix and a source of molecular release of OSMI-4. The influences of OSMI-4 on NSCs and its molecular mechanism were investigated for the first time in this study. Altogether, three-dimensional bioprinting fabrication of NSC- and small molecule drug-laden biomimetic construct may represent a promising therapeutic strategy for SCI repair.

Functional Thermoresponsive Hydrogel Molecule to Material Design for Biomedical Applications

Temperature-induced, rapid changes in the viscosity and reproducible 3-D structure formation makes thermos-sensitive hydrogels an ideal delivery system to act as a cell scaffold or a drug reservoir. Moreover, the hydrogels’ minimum invasiveness, high biocompatibility, and facile elimination from the body have gathered a lot of attention from researchers. This review article attempts to present a complete picture of the exhaustive arena, including the synthesis, mechanism, and biomedical applications of thermosensitive hydrogels. A special section on intellectual property and marketed products tries to shed some light on the commercial potential of thermosensitive hydrogels.

Chitosan-Based Biomaterial Scaffolds for the Repair of Infected Bone Defects

The treatment of infected bone defects includes infection control and repair of the bone defect. The development of biomaterials with anti-infection and osteogenic ability provides a promising strategy for the repair of infected bone defects. Owing to its antibacterial properties, chitosan (an emerging natural polymer) has been widely studied in bone tissue engineering. Moreover, it has been shown that chitosan promotes the adhesion and proliferation of osteoblast-related cells, and can serve as an ideal carrier for bone-promoting substances. In this review, the specific molecular mechanisms underlying the antibacterial effects of chitosan and its ability to promote bone repair are discussed. Furthermore, the properties of several kinds of functionalized chitosan are analyzed and compared with those of pure chitosan. The latest research on the combination of chitosan with different types of functionalized materials and biomolecules for the treatment of infected bone defects is also summarized. Finally, the current shortcomings of chitosan-based biomaterials for the treatment of infected bone defects and future research directions are discussed. This review provides a theoretical basis and advanced design strategies for the use of chitosan-based biomaterials in the treatment of infected bone defects.

In Situ-Forming Collagen/poly-γ-glutamic Acid Hydrogel System with Mesenchymal Stem Cells and Bone Morphogenetic Protein-2 for Bone Tissue Regeneration in a Mouse Calvarial Bone Defect Model

BACKGROUND

Bone marrow-derived mesenchymal stem cells (BMSCs) and bone morphogenetic protein-2 (BMP-2) have been studied for bone repair because they have regenerative potential to differentiate into osteoblasts. The development of injectable and in situ three-dimensional (3D) scaffolds to proliferate and differentiate BMSCs and deliver BMP-2 is a crucial technology in BMSC-based tissue engineering.

METHODS

The proliferation of mouse BMSCs (mBMSCs) in collagen/poly-γ-glutamic acid (Col/γ-PGA) hydrogel was evaluated using LIVE/DEAD and acridine orange and propidium iodide assays. In vitro osteogenic differentiation and the gene expression level of Col/γ-PGA(mBMSC/BMP-2) were assessed by alizarin red S staining and quantitative reverse-transcription polymerase chain reaction. The bone regeneration effect of Col/γ-PGA(mBMSC/BMP-2) was evaluated in a mouse calvarial bone defect model. The cranial bones of the mice were monitored by micro-computed tomography and histological analysis.

RESULTS

The developed Col/γ-PGA hydrogel showed low viscosity below ambient temperature, while it provided a high elastic modulus and viscous modulus at body temperature. After gelation, the Col/γ-PGA hydrogel showed a 3D and interconnected porous structure, which helped the effective proliferation of BMSCs with BMP-2. The Col/γ-PGA (mBMSC/BMP-2) expressed more osteogenic genes and showed effective orthotopic bone formation in a mouse model with a critical-sized bone defect in only 3-4 weeks.

CONCLUSION

The Col/γ-PGA(mBMSC/BMP-2) hydrogel was suggested to be a promising platform by combining collagen as a major component of the extracellular matrix and γ-PGA as a viscosity reducer for easy handling at room temperature in BMSC-based bone tissue engineering scaffolds.

Tunable Thermo-Responsive Properties of Hydroxybutyl Chitosan Oligosaccharide

In this study, a simple method was used to synthesize novel thermosensitive hydroxybutyl chitosan oligosaccharide (HBCOS) by introducing hydroxybutyl groups to C₆–OH of chitosan oligosaccharide (COS) chain. The variation in light scattering demonstrated that HBCOS had good thermosensitive properties and the particle size of HBCOS changed from 2.21–3.58 to 281.23–4,162.40 nm as the temperature increased to a critical temperature (LCST). The LCST of HBCOS (10 mg/ml) decreased from 56.25°C to 40.2°C as the degrees of substitution (DSs) increased from 2.96 to 4.66. The LCST of HBCOS with a DS of 4.66 decreased to 33.5°C and 30°C as the HBCOS and NaCl concentrations increased to 50 mg/ml and 4% (w/v), respectively. Variable-temperature FTIR spectroscopy confirmed that dehydration of hydrophobic chains and the transition of hydrogen bonds were the driving forces for the phase transition of HBCOS. Moreover, HBCOS was not cytotoxic at different concentrations. This work generated a novel thermosensitive HBCOS with tunable thermoresponsive properties and excellent biocompatibility, which may be a potential nanocarrier for the biomedical application.

Effect of Ce-doped bioactive glass/collagen/chitosan nanocomposite scaffolds on the cell morphology and proliferation of rabbit’s bone marrow mesenchymal stem cells-derived osteogenic cells

Background

Cerium-containing materials have wide applications in the biomedical field, because of the mimetic catalytic activities of cerium. The study aims to deeply estimate the biocompatibility of different scaffolds based on Ce-doped nanobioactive glass, collagen, and chitosan using the first passage of rabbit bone marrow mesenchymal stem cells (BM-MSCs) directed to osteogenic lineage by direct and indirect approach. One percentage of glass filler was used (30 wt. %) in the scaffold, while the percentage of CeO₂ in the glass was ranged from 0 to 10 mol. %. Cytotoxicity was evaluated by monitoring of cell morphological changes and reduction in cell proliferation activity of BMMSCs maintained under osteogenic condition using proliferation assays, MTT assay for the direct contact of cells/scaffolds twice in a week, trypan blue and hemocytometer cell counting for indirect contact of cells/scaffolds extracts at day 7. Cell behaviors growth, morphology characteristics were monitored daily under a microscope and cell counting were conducted after 1 week of the incubation of the cells with the extracts of the four composite scaffolds in the osteogenic medium at the end of the week.

Results

Showed that at 24 h after direct contact with composite scaffold, all scaffolds showed proliferation of cells > 50% and increased in cell density on day 7. The scaffold of the highest percentage of CeO₂ in bioactive glass nanoparticles (sample CL/CH/C10) showed the lowest inhibition of cell proliferation (< 25%) at day 7. Moreover, the indirect cell viability test showed that all extracts from the four composite scaffolds did not demonstrate a toxic effect on the cells (inhibition value < 25%).

Conclusion

The addition of CeO₂ to the glass composition improved the biocompatibility of the composite scaffold for the proliferation of rabbit bone marrow mesenchymal stem cells directed to osteogenic lineage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-022-00302-x.

Thermo-responsive chitosan/silk fibroin/amino-functionalized mesoporous silica hydrogels with strong and elastic characteristics for bone tissue engineering

Amino-functionalized mesoporous silica nanoparticles with radially porous architecture were optimally synthesized, and they were used together with silk fibroin and chitosan to produce a type of covalently crosslinked composite hydrogel using genipin as a crosslinker. The optimally achieved composite gels were found to be thermo-responsive at physiological temperature and pH with well-defined injectability. They were also detected to have mechanically strong and elastic characteristics. In addition, these gels showed the ability to release bioactive Si ions suited to an effective dose range in approximately linear manners for a few weeks. Studies on the cell-gel constructs revealed that the composite gels well supported the growth of seeded MC3T3-E1 cells, and the deposition of matrix components. Results obtained from the detection of alkaline phosphatase activity and the matrix mineralization in the cell-gel constructs confirmed that these composite gels had certain osteogenic capacity. The obtained results suggest that these composite gels have promising potential in bone repair and regeneration.

Thermosensitive Chitosan-β-Glycerophosphate Hydrogels as Targeted Drug Delivery Systems: An Overview on Preparation and Their Applications

Today, with the advances in technology and science, more advanced drug delivery formulations are required. One of these new systems is an intelligent hydrogel. These systems are affected by the environment or conditions that become a gel, stay in the circumstance for a certain period, and slowly release the drug. As an advantage, only a lower dose of the drug is required, and it provides less toxicity and minor damage to other tissues. Hydrogels are of different types, including temperature-sensitive, pH-sensitive, ion change-sensitive, and magnetic field-sensitive. In this study, we investigated a kind of temperature-sensitive smart hydrogel, which has a liquid form at room temperature and becomes gel with increasing temperature. Chitosan-β-glycerophosphate hydrogels have been researched and used in many studies. This study investigates the various factors that influence the gelation mechanism, such as gel formation rates, temperature, pH, time, and gel specificity. Hydrogels are used in many drug delivery systems and diseases, including nasal drug delivery, vaginal drug delivery, wound healing, peritoneal adhesion, ophthalmic drug delivery, tissue engineering, and peptide and protein delivery. Overall, the chitosan-β-glycerophosphate hydrogel is a suitable drug carrier for a wide range of drugs. It shows little toxicity to the body, is biodegradable, and is compatible with other organs. This system can be used in different conditions and different medication ways, such as oral, nasal, and injection.

Dual cure (thermal/photo) composite hydrogel derived from chitosan/collagen for in situ 3D bioprinting

In situ 3D printing technologies is a new frontier for highly personalized medicine, which requires suitable bioink with rheology, biocompatibility, and gelation kinetics to support the right shape and mechanical properties of the printed construct. To this end, a facile design of thermo/photo dual cure composite hydrogel was proposed using MHBC and soluble collagen in this study. M/C composite hydrogel exhibited rapid thermo-induced sol-gel transition and contraction, tunable mechanical properties, proper microstructure and biodegradability for 3D cell culture, as well as improve cyto-compatibility, all of which were dependent upon the methacrylation degree of MHBC and M/C ratios. The printability of the optimal formulation (3% MHBC/1% collagen) was validated by its mild printing condition, rapid gelation of bioink at 37 °C and simple postprocessing manipulation. Both desirable printability and cyto-compatibility enable M/C composite hydrogel a potential candidate as bioink to be applied for in situ 3D bioprinting.

Scaffold-free cell-based tissue engineering therapies: advances, shortfalls and forecast

Cell-based scaffold-free therapies seek to develop in vitro organotypic three-dimensional (3D) tissue-like surrogates, capitalising upon the inherent capacity of cells to create tissues with efficiency and sophistication that is still unparalleled by human-made devices. Although automation systems have been realised and (some) success stories have been witnessed over the years in clinical and commercial arenas, in vitro organogenesis is far from becoming a standard way of care. This limited technology transfer is largely attributed to scalability-associated costs, considering that the development of a borderline 3D implantable device requires very high number of functional cells and prolonged ex vivo culture periods. Herein, we critically discuss advancements and shortfalls of scaffold-free cell-based tissue engineering strategies, along with pioneering concepts that have the potential to transform regenerative and reparative medicine.

3D bioprinted neural tissue constructs for spinal cord injury repair

Three-dimensional (3D) bioprinting has emerged as a promising approach to fabricate living neural constructs with anatomically accurate complex geometries and spatial distributions of neural stem cells (NSCs) for spinal cord injury (SCI) repair. The NSC-laden 3D bioprinting, however, still faces some big challenges, such as cumbersome printing process, poor cell viability, and minimal cell-material interaction. To address these issues, we have fabricated NSC-laden scaffolds by 3D bioprinting and explore for the first time their application for in vivo SCI repair. In our strategy, we have developed a novel biocompatible bioink consisting of functional chitosan, hyaluronic acid derivatives, and matrigel. This bioink shows fast gelation (within 20 s) and spontaneous covalent crosslinking capability, facilitating convenient one-step bioprinting of spinal cord-like constructs. Thus-fabricated scaffolds maintain high NSC viability (about 95%), and offer a benign microenvironment that facilitates cell-material interactions and neuronal differentiation for optimal formation of neural network. The in vivo experiment has further demonstrated that the bioprinted scaffolds promoted the axon regeneration and decreased glial scar deposition, leading to significant locomotor recovery of the SCI model rats, which may represent a general and versatile strategy for precise engineering of central nervous system and other neural organs/tissues for regenerative medicine application.

Preparation of hydroxybutyl starch with a high degree of substitution and its application in temperature-sensitive hydrogels

In this work, hydroxybutyl starch prepared by acid, alkali, and acid-base synergistic pretreatments from waxy corn starch exhibited great potential for preparing temperature-sensitive hydrogels. The degree of substitution, morphology, and group structure of hydroxybutyl starch were determined. The hydroxybutyl starch prepared by acid-base synergistic pretreatment had the highest degree of substitution. Relative to the native starch, the surface of hydroxybutyl starch particles was smoother and rounder. The formation, microstructure, and properties of temperature-sensitive hydrogels were also determined in this work. The results indicated that the temperature-sensitive hydrogels containing hydroxybutyl starch had irregular pore structures and higher water absorption rates. As the starch content increased, the pore size of these hydrogels increased and then decreased, the water absorption rate increased and the deswelling rate decreased. The equilibrium swelling ratio of the hydrogel prepared by hydroxybutyl starch was greater than that of native starch.

Generation of Insulin-Producing Cells from Canine Adipose Tissue-Derived Mesenchymal Stem Cells

The potential of mesenchymal stem cells (MSCs) to differentiate into nonmesodermal cells such as pancreatic beta cells has been reported. New cell-based therapy using MSCs for diabetes mellitus is anticipated as an alternative treatment option to insulin injection or islet transplantation in both human and veterinary medicine. Several protocols were reported for differentiation of MSCs into insulin-producing cells (IPCs), but no studies have reported IPCs generated from canine MSCs. The purpose of this study was to generate IPCs from canine adipose tissue-derived MSCs (AT-MSCs) in vitro and to investigate the effects of IPC transplantation on diabetic mice in vivo. Culturing AT-MSCs with the differentiation protocol under a two-dimensional culture system did not produce IPCs. However, spheroid-like small clusters consisting of canine AT-MSCs and human recombinant peptide μ-pieces developed under a three-dimensional (3D) culture system were successfully differentiated into IPCs. The generated IPCs under 3D culture condition were stained with dithizone and anti-insulin antibody. Canine IPCs also showed gene expression typical for pancreatic beta cells and increased insulin secretion in response to glucose stimulation. The blood glucose levels in streptozotocin-induced diabetic mice were decreased after injection with the supernatant of canine IPCs, but the hyperglycemic states of diabetic mice were not improved after transplanting IPCs subcutaneously or intramesenterically. The histological examination showed that the transplanted small clusters of IPCs were successfully engrafted to the mice and included cells positive for insulin by immunofluorescence. Several factors, such as the transplanted cell number, the origin of AT-MSCs, and the differentiation protocol, were considered potential reasons for the inability to improve the hyperglycemic state after IPC transplantation. These findings suggest that canine AT-MSCs can be differentiated into IPCs under a 3D culture system and IPC transplantation may be a new treatment option for dogs with diabetes mellitus.

Controlled Delivery of Insulin-like Growth Factor-1 from Bioactive Glass-Incorporated Alginate-Poloxamer/Silk Fibroin Hydrogels

Thermosensitive alginate–poloxamer (ALG–POL) copolymer with an optimal POL content was synthesized, and it was used to combine with silk fibroin (SF) for building ALG–POL/SF hydrogels with dual network structure. Mesoporous bioactive glass (BG) nanoparticles (NPs) with a high level of mesoporosity and large pore size were prepared and they were employed as a vehicle for loading insulin-like growth factor-1 (IGF-1). IGF-1-loaded BG NPs were embedded into ALG–POL/SF hydrogels to achieve the controlled delivery of IGF-1. The resulting IGF-1-loaded BG/ALG–POL/SF gels were found to be injectable with their sol-gel transition near physiological temperature and pH. Rheological measurements showed that BG/ALG–POL/SF gels had their elastic modulus higher than 5kPa with large ratio of elastic modulus to viscous modulus, indicative of their mechanically strong features. The dry BG/ALG–POL/SF gels were seen to be highly porous with well-interconnected pore characteristics. The gels loaded with varied amounts of IGF-1 showed abilities to administer IGF-1 release in approximately linear manners for a few weeks while effectively preserving the bioactivity of encapsulated IGF-1. Results suggest that such constructed BG/ALG–POL/SF gels can function as a promising injectable biomaterial for bone tissue engineering applications.

Alginate-poloxamer/silk fibroin hydrogels with covalently and physically cross-linked networks for cartilage tissue engineering

Poloxamer was grafted onto alginate and the optimally synthesized alginate-poloxamer (ALG-POL) copolymer was combined with silk fibroin (SF) to produce thermosensitive ALG-POL/SF hydrogels with covalently and physically crosslinked networks. The formulated ALG-POL/SF gels were found to be injectable with sol-gel transitions near physiological temperature and pH. Rheological measurements showed that some ALG-POL/SF gels had their elastic modulus of around 5 kPa or higher with large ratio of elastic modulus to viscous modulus, indicative of their mechanically strong feature. The achieved ALG-POL/SF gels exhibited concurrent enhancement in strength and elasticity when compared to the gels built with either ALG-POL or SF alone. The microscopic insight into dry ALG-POL/SF gels validated that they were highly porous with well-interconnected pore characteristics. These ALG-POL/SF gels showed abilities to support the in-growth of seeded chondrocytes while effectively maintaining their chondrogenic phenotype. Results suggest promising attributes of ALG-POL/SF gels as alternative biomaterial for cartilage tissue engineering.

Dual-enzymatically crosslinked hyaluronic acid hydrogel as a long-time 3D stem cell culture system

Stem cell-based tissue engineering shows enormous potential for regenerative medicine. Three-dimensional (3D) stem cell culture is the most basic aspect of tissue engineering. However, achievement of a perfect scaffold for highly efficient 3D cell culture is currently still limited. Herein, a new hyaluronic acid hydrogel dual-enzymatically crosslinked by horseradish peroxidase and choline oxidase is developed as a 3D stem cell culture system. This hydrogel possesses superior stability over two months, controllable biodegradability with hyaluronidases, a high swelling ratio exceeding 6000%, and excellent cytocompatibility in vitro and biocompatibility in vivo. More importantly, a long-time and highly cellular activity 3D culture of bone marrow-derived mesenchymal stem cells was achieved in vitro over 20 days. All these encouraging results highlight the great potential of this new hydrogel for 3D culture and tissue engineering.

Thermoresponsive Chitosan/DOPA-Based Hydrogel as an Injectable Therapy Approach for Tissue-Adhesion and Hemostasis

Chitosan (CS) hydrogels are widely used in wound hemostatic agents due to their superior biocompatibility, biodegradability, and hemostatic effect. However, most of them fail to achieve great hemostatic effect because of poor adhesion to bleeding tissues. Also, the conventional implantation surgery of hemostatic hydrogels to internal bleeding wounds may cause secondary trauma to the human body. In this work, catechol-hydroxybutyl chitosan (HBCS-C) has been designed and prepared by grafting hydroxybutyl groups and catechol groups to the CS backbones. The multifunctional HBCS-C hydrogels are fabricated with the properties of thermosensitivity, injectability, tissue-adhesion, biodegradation, biocompatibility, and wound hemostasis. They exhibit excellent liquid-gel transition at different temperatures, through the changes of hydrophilic-hydrophobic interaction and hydrogen bonds generating from hydroxybutyl groups. By the multiple interactions between catechol groups/amino groups and tissues, the biocompatible hydrogels can strongly adhere on the surface of tissue. To further study, the bleeding rat-liver models are made to evaluate the hemostatic effects. After injecting the hydrogel precursor solution into the rat body, the hydrogels are not only formed in situ within 30 s but are also firmly adhered to the bleeding tissues which shows effective hemostasis. The injectability and tissue-adhesion improvement in this study gives a new insight into hemostatic agents, and the multifunctional hydrogels have a great potential in the biomedical application.

Sustained release of human platelet lysate growth factors by thermosensitive hydroxybutyl chitosan hydrogel promotes skin wound healing in rats

This study evaluated the effect of thermosensitive hydroxybutyl chitosan (HBC) hydrogel loaded with human platelet lysate (hPL) on skin wound healing in rats. hPLs were generated by freeze-thaw method of platelet-rich plasma from healthy donors. Successful grafting of hydroxybutyl group to chitosan molecular chain to obtain HBC hydrogel was confirmed by Fourier-transform infrared spectroscopy. HBC/hPL was prepared by combining 10% (vol/vol) hPL with HBC solution. Surface morphologies were determined by Scanning Electron Microscopy, rheological properties were measured by rheometer, and sustained release of factors from HBC/hPL was measured by enzyme-linked immunoassay. We evaluated the in vitro effect of HBC/hPL on human umbilical cord vein endothelial cell (HUVEC) proliferation, migration, and tube formation. The effect of growth factors released from HBC/hPL in promoting skin wound healing was evaluated by gross observation, histology, immunohistochemistry, and immunofluorescence in vivo. Rheological analyses indicated the gelation temperatures of HBC and HBC/hPL were 17 and 14°C, respectively. ELISA showed sustained release of human platelet-derived growth factor, basic fibroblast growth factor, and transforming growth factor-β1 from HBC/hPL hydrogel. In vitro studies revealed HBC/hPL promoted greater levels of HUVECs proliferation, migration, and tube formation than the HBC and control groups. In vivo studies showed better wound healing, greater amounts of newly formed collagen, as well as neovascular and neo-epidermis markers in the wound site of HBC/hPL-treated group compared to the HBC and control groups. HBC/hPL is a promising potential therapeutic agent for promoting skin wound healing via the sustained release of growth factors.

Chitosan based bioactive materials in tissue engineering applications-A review

In recent years, there have been increasingly rapid advances of using bioactive materials in tissue engineering applications. Bioactive materials constitute many different structures based upon ceramic, metallic or polymeric materials, and can elicit specific tissue responses. However, most of them are relatively brittle, stiff, and difficult to form into complex shapes. Hence, there has been a growing demand for preparing materials with tailored physical, biological, and mechanical properties, as well as predictable degradation behavior. Chitosan-based materials have been shown to be ideal bioactive materials due to their outstanding properties such as formability into different structures, and fabricability with a wide range of bioactive materials, in addition to their biocompatibility and biodegradability. This review highlights scientific findings concerning the use of innovative chitosan-based bioactive materials in the fields of tissue engineering, with an outlook into their future applications. It also covers latest developments in terms of constituents, fabrication technologies, structural, and bioactive properties of these materials that may represent an effective solution for tissue engineering materials, making them a realistic clinical alternative in the near future.

Microcarriers for Upscaling Cultured Meat Production

Due to the considerable environmental impact and the controversial animal welfare associated with industrial meat production, combined with the ever-increasing global population and demand for meat products, sustainable production alternatives are indispensable. In 2013, the world's first laboratory grown hamburger made from cultured muscle cells was developed. However, coming at a price of $300.000, and being produced manually, substantial effort is still required to reach sustainable large-scale production. One of the main challenges is scalability. Microcarriers (MCs), offering a large surface/volume ratio, are the most promising candidates for upscaling muscle cell culture. However, although many MCs have been developed for cell lines and stem cells typically used in the medical field, none have been specifically developed for muscle stem cells and meat production. This paper aims to discuss the MCs' design criteria for skeletal muscle cell proliferation and subsequently for meat production based on three scenarios: (1) MCs are serving only as a temporary substrate for cell attachment and proliferation and therefore they need to be separated from the cells at some stage of the bioprocess, (2) MCs serve as a temporary substrate for cell proliferation but are degraded or dissolved during the bioprocess, and (3) MCs are embedded in the final product and therefore need to be edible. The particularities of each of these three bioprocesses will be discussed from the perspective of MCs as well as the feasibility of a one-step bioprocess. Each scenario presents advantages and drawbacks, which are discussed in detail, nevertheless the third scenario appears to be the most promising one for a production process. Indeed, using an edible material can limit or completely eliminate dissociation/degradation/separation steps and even promote organoleptic qualities when embedded in the final product. Edible microcarriers could also be used as a temporary substrate similarly to scenarios 1 and 2, which would limit the risk of non-edible residues.

A Self-Setting Hydrogel of Silylated Chitosan and Cellulose for the Repair of Osteochondral Defects: From in vitro Characterization to Preclinical Evaluation in Dogs

Articular cartilage (AC) may be affected by many injuries including traumatic lesions that predispose to osteoarthritis. Currently there is no efficient cure for cartilage lesions. In that respect, new strategies for regenerating AC are contemplated with interest. In this context, we aim to develop and characterize an injectable, self-hardening, mechanically reinforced hydrogel (Si-HPCH) composed of silanised hydroxypropymethyl cellulose (Si-HPMC) mixed with silanised chitosan. The in vitro cytocompatibility of Si-HPCH was tested using human adipose stromal cells (hASC). In vivo, we first mixed Si-HPCH with hASC to observe cell viability after implantation in nude mice subcutis. Si-HPCH associated or not with canine ASC (cASC), was then tested for the repair of osteochondral defects in canine femoral condyles. Our data demonstrated that Si-HPCH supports hASC viability in culture. Moreover, Si-HPCH allows the transplantation of hASC in the subcutis of nude mice while maintaining their viability and secretory activity. In the canine osteochondral defect model, while the empty defects were only partially filled with a fibrous tissue, defects filled with Si-HPCH with or without cASC, revealed a significant osteochondral regeneration. To conclude, Si-HPCH is an injectable, self-setting and cytocompatible hydrogel able to support the in vitro and in vivo viability and activity of hASC as well as the regeneration of osteochondral defects in dogs when implanted alone or with ASC.

Enhanced efficiency in isolation and expansion of hAMSCs via dual enzyme digestion and micro-carrier

A two-stage method of obtaining viable human amniotic stem cells (hAMSCs) in large-scale is described. First, human amniotic stem cells are isolated via dual enzyme (collagenase II and DNAase I) digestion. Next, relying on a culture of the cells from porous chitosan-based microspheres in vitro, high purity hAMSCs are obtained in large-scale. Dual enzymatic (collagenase II and DNase I) digestion provides a primary cell culture and first subculture with a lower contamination rate, higher purity and a larger number of isolated cells. The obtained hAMSCs were seeded onto chitosan microspheres (CM), gelatin-chitosan microspheres (GCM) and collagen-chitosan microspheres (CCM) to produce large numbers of hAMSCs for clinical trials. Growth activity measurement and differentiation essays of hAMSCs were realized. Within 2 weeks of culturing, GCMs achieved over 1.28 ± 0.06 × 107 hAMSCs whereas CCMs and CMs achieved 7.86 ± 0.11 × 106 and 1.98 ± 0.86 × 106 respectively within this time. In conclusion, hAMSCs showed excellent attachment and viability on GCM-chitosan microspheres, matching the hAMSCs' normal culture medium. Therefore, dual enzyme (collagenase II and DNAase I) digestion may be a more useful isolation process and culture of hAMSCs on porous GCM in vitro as an ideal environment for the large-scale expansion of highly functional hAMSCs for eventual use in stem cell-based therapy.

HBC-nanofiber hydrogel scaffolds with 3D printed internal microchannels for enhanced cartilage differentiation

HBC-nanofiber hydrogel scaffolds with 3D printed internal microchannels have been developed to provide a multifunctional biomimetic microenvironment for hMSC chondrogenesis.

Enhanced dual network hydrogels consisting of thiolated chitosan and silk fibroin for cartilage tissue engineering

Thiolated chitosan (CS-NAC) was synthesized and the selected CS-NAC was used together with silk fibroin (SF) to produce dual network CS-NAC/SF hydrogels. The CS-NAC/SF solutions with formulated compositions were able to form hydrogels at physiological temperature and pH. Rheological measurements showed that elastic modulus of some CS-NAC/SF gels could reach around 3 kPa or higher and was much higher than their respective viscous modulus, indicating that they behaved like strong gels. Deformation measurements verified that CS-NAC/SF gels had well-defined elasticity. The optimized CS-NAC/SF gels exhibited jointly enhanced properties in terms of strength, stiffness and elasticity when compared to the gels resulted from either CS-NAC or SF. Examinations of dry CS-NAC/SF gels revealed that they were highly porous with well-interconnected pore features. Cell culture demonstrated that CS-NAC/SF gels supported the growth of chondrocytes while effectively maintaining their phenotype. Results suggest that these dual network gels have promising potential in cartilage repair.

In vitro and in vivo effects of insulin-producing cells generated by xeno-antigen free 3D culture with RCP piece

To establish widespread cell therapy for type 1 diabetes mellitus, we aimed to develop an effective protocol for generating insulin-producing cells (IPCs) from adipose-derived stem cells (ADSCs). We established a 3D culture using a human recombinant peptide (RCP) petaloid μ-piece with xeno-antigen free reagents. Briefly, we employed our two-step protocol to differentiate ADSCs in 96-well dishes and cultured cells in xeno-antigen free reagents with 0.1 mg/mL RCP μ-piece for 7 days (step 1), followed by addition of histone deacetylase inhibitor for 14 days (step 2). Generated IPCs were strongly stained with dithizone, anti-insulin antibody at day 21, and microstructures resembling insulin secretory granules were detected by electron microscopy. Glucose stimulation index (maximum value, 4.9) and MAFA mRNA expression were significantly higher in 3D cultured cells compared with conventionally cultured cells (P < 0.01 and P < 0.05, respectively). The hyperglycaemic state of streptozotocin-induced diabetic nude mice converted to normoglycaemic state around 14 days after transplantation of 96 IPCs under kidney capsule or intra-mesentery. Histological evaluation revealed that insulin and C-peptide positive structures existed at day 120. Our established xeno-antigen free and RCP petaloid μ-piece 3D culture method for generating IPCs may be suitable for clinical application, due to the proven effectiveness in vitro and in vivo.