Regeneration of the Osteochondral Defect by a Wollastonite and Macroporous Fibrin Biphasic Scaffold

Accelerated Osteogenic Response of Electrodynamically Stimulated Mg1-xCaxSi1-xZrxO3 (x = 0-0.4) Bioelectrets

MgSiO3-based biodegradable ceramics demonstrated remarkable potential for treating small-scale bone defects and temporary bone replacement. In addition, the dissolution behavior of MgSiO3 bioceramics can be tuned by doping of Ca and Zr elements at Mg and Si sites, respectively. The present study reported the influence of formation of Ca- and Zr-codoped Mg1-xCaxSi1-xZrxO3 (x = 0, 0.1, 0.2, 0.3, and 0.4) bioelectrets and electrodynamic stimulation toward improving their osteogenic response. Mg1-xCaxSi1-xZrxO3 electrets were successfully synthesized by a solid-state route. A detailed X-ray photoelectron spectroscopy (XPS) analyses revealed that the electrets produced oxygen-deficient active sites. The formation of Mg1-xCaxSi1-xZrxO3 electrets significantly increased the surface hydrophilicity. Inductively coupled plasma (ICP) analyses were used to examine the leaching behavior of Ca/Zr-codoped MgSiO3 bioceramics. In vitro cell culture analyses indicated that the osteogenesis of MG-63 cells was remarkably enhanced on the electrodynamic field-treated Mg1-xCaxSi1-xZrxO3 bioelectrets as compared to hydroxyapatite (HA). Moreover, a better osteogenic response was observed for higher concentrations of Ca (0.3 and 0.4) and Zr (0.3 and 0.4) doping in the MgSiO3 bioelectrets. Further, the mechanism of enhanced cellular functionality was revealed by the measurement of intracellular Ca2+.

Multiphasic scaffolds for the repair of osteochondral defects: Outcomes of preclinical studies

Osteochondral defects are caused by injury to both the articular cartilage and subchondral bone within skeletal joints. They can lead to irreversible joint damage and increase the risk of progression to osteoarthritis. Current treatments for osteochondral injuries are not curative and only target symptoms, highlighting the need for a tissue engineering solution. Scaffold-based approaches can be used to assist osteochondral tissue regeneration, where biomaterials tailored to the properties of cartilage and bone are used to restore the defect and minimise the risk of further joint degeneration. This review captures original research studies published since 2015, on multiphasic scaffolds used to treat osteochondral defects in animal models. These studies used an extensive range of biomaterials for scaffold fabrication, consisting mainly of natural and synthetic polymers. Different methods were used to create multiphasic scaffold designs, including by integrating or fabricating multiple layers, creating gradients, or through the addition of factors such as minerals, growth factors, and cells. The studies used a variety of animals to model osteochondral defects, where rabbits were the most commonly chosen and the vast majority of studies reported small rather than large animal models. The few available clinical studies reporting cell-free scaffolds have shown promising early-stage results in osteochondral repair, but long-term follow-up is necessary to demonstrate consistency in defect restoration. Overall, preclinical studies of multiphasic scaffolds show favourable results in simultaneously regenerating cartilage and bone in animal models of osteochondral defects, suggesting that biomaterials-based tissue engineering strategies may be a promising solution.

Is 3D Printing Promising for Osteochondral Tissue Regeneration?

Osteochondral tissue regeneration is quite difficult to achieve due to the complexity of its organization. In the design of these complex multilayer structures, a fabrication method, 3D printing, started to be employed, especially by using extrusion, stereolithography and inkjet printing approaches. In this paper, the designs are discussed including biphasic, triphasic, and gradient structures which aim to mimic the cartilage and the calcified cartilage and the whole osteochondral tissue closely. In the first section of the review paper, 3D printing of hydrogels including gelatin methacryloyl (GelMa), alginate, and polyethylene glycol diacrylate (PEGDA) are discussed. However, their physical and biological properties need to be augmented, and this generally is achieved by blending the hydrogel with other, more durable, less hydrophilic, polymers. These scaffolds are very suitable to carry growth factors, such as TGF-β1, to further stimulate chondrogenesis. The bone layer is mimicked by printing calcium phosphates (CaPs) or bioactive glasses together with the hydrogels or as a component of another polymer layer. The current research findings indicate that polyester (i.e. polycaprolactone (PCL), polylactic acid (PLA) and poly(lactide-co-glycolide) (PLGA)) reinforced hydrogels may more successfully mimic the complex structure of osteochondral tissue. Moreover, more recent printing methods such as melt electrowriting (MEW), are being used to integrate polyester fibers to enhance the mechanical properties of hydrogels. Additionally, polyester scaffolds that are 3D printed without hydrogels are discussed after the hydrogel-based scaffolds. In this review paper, the relevant studies are analyzed and discussed, and future work is recommended with support of tables of designed scaffolds. The outcome of the survey of the field is that 3D printing has significant potential to contribute to osteochondral tissue repair.

A triphasic biomimetic BMSC-loaded scaffold for osteochondral integrated regeneration in rabbits and pigs

Osteochondral tissue involves cartilage, calcified cartilage and subchondral bone. These tissues differ significantly in chemical compositions, structures, mechanical properties and cellular compositions. Therefore, the repairing materials face different osteochondral tissue regeneration needs and rates. In this study, we fabricated an osteochondral tissue-inspired triphasic material, which was composed of a poly(lactide-co-glycolide) (PLGA) scaffold loaded with fibrin hydrogel, bone marrow stromal cells (BMSCs) and transforming growth factor-β1 (TGF-β1) for cartilage tissue, a bilayer poly(L-lactide-co-caprolactone) (PLCL)-fibrous membrane loaded with chondroitin sulfate and bioactive glass, respectively, for calcified cartilage, and a 3D-printed calcium silicate ceramic scaffold for subchondral bone. The triphasic scaffold was press-fitted into the osteochondral defects in rabbit (cylindrical defects with a diameter of 4 mm and a depth of 4 mm) and minipig knee joints (cylindrical defects with a diameter of 10 mm and a depth of 6 mm). The μ-CT and histological analysis showed that the triphasic scaffold was partly degraded, and significantly promoted the regeneration of hyaline cartilage after they were implanted in vivo. The superficial cartilage showed good recovery and uniformity. The calcified cartilage layer (CCL) fibrous membrane was in favor of a better cartilage regeneration morphology, a continuous cartilage structure and less fibrocartilage tissue formation. The bone tissue grew into the material, while the CCL membrane limited bone overgrowth. The newly generated osteochondral tissues were well integrated with the surrounding tissues too.

Bioinks adapted for in situ bioprinting scenarios of defect sites: a review

In situ bioprinting provides a reliable solution to the problem of in vitro tissue culture and vascularization by printing tissue directly at the site of injury or defect and maturing the printed tissue using the natural cell microenvironment in vivo. As an emerging field, in situ bioprinting is based on computer-assisted scanning results of the defect site and is able to print cells directly at this site with biomaterials, bioactive factors, and other materials without the need to transfer prefabricated grafts as with traditional in vitro 3D bioprinting methods, and the resulting grafts can accurately adapt to the target defect site. However, one of the important reasons hindering the development of in situ bioprinting is the absence of suitable bioinks. In this review, we will summarize bioinks developed in recent years that can adapt to in situ printing scenarios at the defect site, considering three aspects: the in situ design strategy of bioink, the selection of commonly used biomaterials, and the application of bioprinting to different treatment scenarios.

Design and bioprinting for tissue interfaces

Tissue interfaces include complex gradient structures formed by transitioning of biochemical and mechanical properties in micro-scale. This characteristic allows the communication and synchronistic functioning of two adjacent but distinct tissues. It is particularly challenging to restore the function of these complex structures by transplantation of scaffolds exclusively produced by conventional tissue engineering methods. Three-dimensional (3D) bioprinting technology has opened an unprecedented approach for precise and graded patterning of chemical, biological and mechanical cues in a single construct mimicking natural tissue interfaces. This paper reviews and highlights biochemical and biomechanical design for 3D bioprinting of various tissue interfaces, including cartilage-bone, muscle-tendon, tendon/ligament-bone, skin, and neuro-vascular/muscular interfaces. Future directions and translational challenges are also provided at the end of the paper.

Integrated gradient tissue-engineered osteochondral scaffolds: Challenges, current efforts and future perspectives

The osteochondral defect repair has been most extensively studied due to the rising demand for new therapies to diseases such as osteoarthritis. Tissue engineering has been proposed as a promising strategy to meet the demand of simultaneous regeneration of both cartilage and subchondral bone by constructing integrated gradient tissue-engineered osteochondral scaffold (IGTEOS). This review brought forward the main challenges of establishing a satisfactory IGTEOS from the perspectives of the complexity of physiology and microenvironment of osteochondral tissue, and the limitations of obtaining the desired and required scaffold. Then, we comprehensively discussed and summarized the current tissue-engineered efforts to resolve the above challenges, including architecture strategies, fabrication techniques and in vitro/in vivo evaluation methods of the IGTEOS. Especially, we highlighted the advantages and limitations of various fabrication techniques of IGTEOS, and common cases of IGTEOS application. Finally, based on the above challenges and current research progress, we analyzed in details the future perspectives of tissue-engineered osteochondral construct, so as to achieve the perfect reconstruction of the cartilaginous and osseous layers of osteochondral tissue simultaneously. This comprehensive and instructive review could provide deep insights into our current understanding of IGTEOS.

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Providing main challenges to establish integrated gradient osteochondral scaffold.

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Discussing the current tissue-engineered efforts to resolve the above challenges.

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Highlighting construct techniques, and evaluation index and methods of IGTEOS.

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Discussing the future perspectives to achieve perfect osteochondral reconstruction.

Application of Hydrogels as Sustained-Release Drug Carriers in Bone Defect Repair

Large bone defects resulting from trauma, infection and tumors are usually difficult for the body's repair mechanisms to heal spontaneously. Generally, various types of bones and orthopedic implants are adopted to enhance bone repair and regeneration in the clinic. Due to the limitations of traditional treatments, bone defect repair is still a compelling challenge for orthopedic surgeons. In recent years, bone tissue engineering has become a potential option for bone repair and regeneration. Amidst the various scaffolds for bone tissue engineering applications, hydrogels are considered a new type of non-toxic, non-irritating and biocompatible materials, which are widely used in the biomedicine field currently. Some studies have demonstrated that hydrogels can provide a three-dimensional network structure similar to a natural extracellular matrix for tissue regeneration and can be used to transport cells, biofactors, nutrients and drugs. Therefore, hydrogels may have the potential to be multifunctional sustained-release drug carriers in the treatment of bone defects. The recent applications of different types of hydrogels in bone defect repair were briefly reviewed in this paper.

High-Strength, Biomimetic Functional Chitosan-Based Hydrogels for Full-Thickness Osteochondral Defect Repair

Fabrication of a hydrogel scaffold for full-thickness osteochondral defect repair remains a grand challenge. Developing layered and multiphasic hydrogels to mimic the intrinsic hierarchical structure of the osteochondral unit is a promising strategy. Chitosan-based hydrogels are widely applied for biomedical applications. However, insufficient mechanical strength and lack of biological cues to restore damaged cartilage and subchondral tissue significantly hinder their application in osteochondral tissue engineering. In this study, a strong and tough, osteochondral-mimicking functional chitosan-based hydrogel (bilayer-gel) with an in situ mineralized, osteoconductive lower layer and a basic fibroblast growth factor (bFGF)-incorporated, chondrogenic inducing upper layer was developed. The obtained bilayer-gel showed a depth-dependent gradient pore structure and composition. The strong double crosslinked hydrogel network and the homogeneous deposition of hydroxyapatite nanoparticles (HAp) at the lower layer provided a compressive strength of up to 2.5 MPa and a compressive strain of up to 40%. In vitro study showed that the bilayer-gel facilitates both chondrogenic differentiation in the upper layer and osteogenic differentiation in the lower layer. In vivo implantation revealed that the bilayer-gel could simultaneously promote hyaline cartilage and subchondral bone formation, thus resulting in an improved osteochondral reconstruction outcome. The present bilayer-gel thus shows great potential for full-thickness osteochondral defect repair.

In Vivo Application of Silica-Derived Inks for Bone Tissue Engineering: A 10-Year Systematic Review

As the need for efficient, sustainable, customizable, handy and affordable substitute materials for bone repair is critical, this systematic review aimed to assess the use and outcomes of silica-derived inks to promote in vivo bone regeneration. An algorithmic selection of articles was performed following the PRISMA guidelines and PICO method. After the initial selection, 51 articles were included. Silicon in ink formulations was mostly found to be in either the native material, but associated with a secondary role, or to be a crucial additive element used to dope an existing material. The inks and materials presented here were essentially extrusion-based 3D-printed (80%), and, overall, the most investigated animal model was the rabbit (65%) with a femoral defect (51%). Quality (ARRIVE 2.0) and risk of bias (SYRCLE) assessments outlined that although a large majority of ARRIVE items were “reported”, most risks of bias were left “unclear” due to a lack of precise information. Almost all studies, despite a broad range of strategies and formulations, reported their silica-derived material to improve bone regeneration. The rising number of publications over the past few years highlights Si as a leverage element for bone tissue engineering to closely consider in the future.

Photo-Crosslinkable Hydrogels for 3D Bioprinting in the Repair of Osteochondral Defects: A Review of Present Applications and Future Perspectives

An osteochondral defect is a common and frequent disease in orthopedics and treatment effects are not good, which can be harmful to patients. Hydrogels have been applied in the repair of cartilage defects. Many studies have reported that hydrogels can effectively repair osteochondral defects through loaded cells or non-loaded cells. As a new type of hydrogel, photo-crosslinked hydrogel has been widely applied in more and more fields. Meanwhile, 3D bioprinting serves as an attractive platform to fabricate customized tissue-engineered substitutes from biomaterials and cells for the repair or replacement of injured tissues and organs. Although photo-crosslinkable hydrogel-based 3D bioprinting has some advantages for repairing bone cartilage defects, it also has some disadvantages. Our aim of this paper is to review the current status and prospect of photo-crosslinkable hydrogel-based 3D bioprinting for repairing osteochondral defects.

Modulation of 3D Printed Calcium-Deficient Apatite Constructs with Varying Mn Concentrations for Osteochondral Regeneration via Endochondral Differentiation

Osteochondral regeneration remains a vital problem in clinical situations affecting both bone and cartilage tissues due to the low regeneration ability of cartilage tissue. Additionally, the simultaneous regeneration of bone and cartilage is difficult to attain due to their dissimilar nature. Thus, fabricating a single scaffold for both bone and cartilage regeneration remains challenging. Biomaterials are frequently employed to promote tissue restoration, but they still cannot replicate the structure of native tissue. This study aims to create a single biomaterial that could be used to regenerate both bone and cartilage. This study focuses on synthesizing calcium-deficient apatite (CDA) with the gradual addition of manganese. The phase stability and the effect of heat treatment on manganese-doped CDA were studied using X-ray diffraction (XRD) and Rietveld refinement. The obtained powders were tested for their 3-dimensional (3D) printing ability by fabricating cuboidal 3D structures. The 3D printed scaffolds were examined for external topography using field-emission scanning electron microscopy (FE-SEM) and were subjected to compression testing. In vitro biocompatibility and differentiation studies were performed to access their biocompatibility and differentiation capabilities. Reverse transcription-quantitative PCR (RT-qPCR) analysis was done to determine the gene expression of bone- and cartilage-specific markers. Mn helps in stabilizing the β-TCP phase beyond its sintering temperature without being degraded to α-TCP. Mn addition in CDA improves the compressive strength of the fabricated scaffolds while keeping them biocompatible. The concentrations of Mn in the CDA ceramic were found to influence the differentiation behavior of MSCs in the fabricated scaffolds. Mn-doped CDA is a promising candidate to be used as a substitute material for bone, cartilage, and osteochondral defects to facilitate repair and regeneration via endochondral differentiation. 3D printing can assist in the fabrication of a multifunctional single-unit scaffold with varied Mn concentrations, which might be able to generate the two tissues in situ in an osteochondral defect.

[Research progress of in-situ three dimensional bio-printing technology for repairing bone and cartilage injuries]

OBJECTIVE

To review the research progress of in-situ three dimensional (3D) bio-printing technology in the repair of bone and cartilage injuries.

METHODS

Literature on the application of in-situ 3D bio-printing technology to repair bone and cartilage injuries at home and abroad in recent years was reviewed, analyzed, and summarized.

RESULTS

As a new tissue engineering technology, in-situ 3D bio-printing technology is mainly applied to repair bone, cartilage, and skin tissue injuries. By combining biomaterials, bioactive substances, and cells, tissue is printed directly at the site of injury or defect. At present, the research on the technology mainly focuses on printing mode, bio-ink, and printing technology; the application research in the field of bone and cartilage mainly focuses on pre-vascularization, adjusting the composition of bio-ink, improving scaffold structure, printing technology, loading drugs, cells, and bioactive factors, so as to promote tissue injury repair.

CONCLUSION

Multiple animal experiments have confirmed that in-situ 3D bio-printing technology can construct bone and cartilage tissue grafts in a real-time, rapid, and minimally invasive manner. In the future, it is necessary to continue to develop bio-inks suitable for specific tissue grafts, as well as combine with robotics, fusion imaging, and computer-aided medicine to improve printing efficiency.

Layer-specific stem cell differentiation in tri-layered tissue engineering biomaterials: Towards development of a single-stage cell-based approach for osteochondral defect repair

Successful repair of osteochondral defects is challenging, due in part to their complex gradient nature. Tissue engineering approaches have shown promise with the development of layered scaffolds that aim to promote cartilage and bone regeneration within the defect. The clinical potential of implanting these scaffolds cell-free has been demonstrated, whereby cells from the host bone marrow MSCs infiltrate the scaffolds and promote cartilage and bone regeneration within the required regions of the defect. However, seeding the cartilage layer of the scaffold with a chondrogenic cell population prior to implantation may enhance cartilage tissue regeneration, thus enabling the treatment of larger defects. Here the development of a cell seeding approach capable of enhancing articular cartilage repair without the requirement for in vitro expansion of the cell population is explored. The intrinsic ability of a tri-layered scaffold previously developed in our group to direct stem cell differentiation in each layer of the scaffold was first demonstrated. Following this, the optimal chondrogenic cell seeding approach capable of enhancing the regenerative capacity of the tri-layered scaffold was demonstrated with the highest levels of chondrogenesis achieved with a co-culture of rapidly isolated infrapatellar fat pad MSCs (FPMSCs) and chondrocytes (CCs). The addition of FPMSCs to a relatively small number of CCs led to a 7.8-fold increase in the sGAG production over chondrocytes in mono-culture. This cell seeding approach has the potential to be delivered within a single-stage approach, without the requirement for costly in vitro expansion of harvested cells, to achieve rapid repair of osteochondral defects.

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Tri-layered scaffold capable of directing layer specific stem cell differentiation.

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Potential of cell seeding regimes to enhance chondrogenic repair explored.

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Optimal cell seeding regime was an infrapatellar fat pad MSC:chondrocyte coculture.

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Adding infrapatellar fat pad MSCs to chondrocytes led to >7-fold increase in sGAG.

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This cell-seeded scaffold has potential for rapid repair of osteochondral defects.

A bilayered scaffold with segregated hydrophilicity-hydrophobicity enables reconstruction of goat hierarchical temporomandibular joint condyle cartilage

Temporomandibular joint (TMJ) supports chewing, talking or other daily oral activities. So far, it still remains a great challenge to treat the defected TMJ condyle cartilage through tissue engineering technology. Herein, a bilayered scaffold is designed to fully reconstruct the different cartilage matrices of TMJ condyle under same induction condition. The bilayered scaffold with segregated hydrophobicity-hydrophilicity in top and bottom layer is prepared from a low and high content of polyethylene glycol (PEG) crosslinked poly (L-glutamic acid)-g-polycaprolactone (PLGA-g-PCL). The hydrophobic aggregates in top layer support the adhesion and spread of bone mesenchymal stem cells (BMSCs), thus inducing the differentation towards fibrocartilage; while aggregates (spheroids) are formed on the hydrophlic bottom layer, showing a preferable hyaline differentiation pathway under same chondrogenic induction in vitro. After 14 d in vitro induction, the scaffold/BMSCs construct is implanted in goat TMJ condyle defects. The post-operative outcome after 2 months demonstrates that the defects are fully covered by neo-cartilage. And the regenerated hierarchical TMJ condyle cartilage perfectly consist of ordered fibrocartilage and hyaline cartilage, which is same as natural condyle cartilage. These results corroborate that this bilayered scaffold with segregated hydrophilicity-hydrophobicity carrying induced BMSCs is a promising for treatment of TMJ condyle cartilage defects.

Tissue Engineering in Musculoskeletal Tissue: A Review of the Literature

Tissue engineering refers to the attempt to create functional human tissue from cells in a laboratory. This is a field that uses living cells, biocompatible materials, suitable biochemical and physical factors, and their combinations to create tissue-like structures. To date, no tissue engineered skeletal muscle implants have been developed for clinical use, but they may represent a valid alternative for the treatment of volumetric muscle loss in the near future. Herein, we reviewed the literature and showed different techniques to produce synthetic tissues with the same architectural, structural and functional properties as native tissues.

Tough and tunable scaffold-hydrogel composite biomaterial for soft-to-hard musculoskeletal tissue interfaces

Tendon inserts into bone via a fibrocartilaginous interface (enthesis) that reduces mechanical strain and tissue failure. Despite this toughening mechanism, tears occur because of acute (overload) or degradative (aging) processes. Surgically fixating torn tendon into bone results in the formation of a scar tissue interface with inferior biomechanical properties. Progress toward enthesis regeneration requires biomaterial approaches to protect cells from high levels of interfacial strain. We report an innovative tissue reinforcement strategy: a stratified scaffold containing osseous and tendinous tissue compartments attached through a continuous polyethylene glycol (PEG) hydrogel interface. Tuning the gelation kinetics of the hydrogel modulates integration with the flanking compartments and yields biomechanical performance advantages. Notably, the hydrogel interface reduces formation of strain concentrations between tissue compartments in conventional stratified biomaterials that can have deleterious biological effects. This design of mechanically robust stratified composite biomaterials may be appropriate for a broad range of tendon and ligament-to-bone insertions.

Scaffolding Strategies for Tissue Engineering and Regenerative Medicine Applications

During the past two decades, tissue engineering and the regenerative medicine field have invested in the regeneration and reconstruction of pathologically altered tissues, such as cartilage, bone, skin, heart valves, nerves and tendons, and many others. The 3D structured scaffolds and hydrogels alone or combined with bioactive molecules or genes and cells are able to guide the development of functional engineered tissues, and provide mechanical support during in vivo implantation. Naturally derived and synthetic polymers, bioresorbable inorganic materials, and respective hybrids, and decellularized tissue have been considered as scaffolding biomaterials, owing to their boosted structural, mechanical, and biological properties. A diversity of biomaterials, current treatment strategies, and emergent technologies used for 3D scaffolds and hydrogel processing, and the tissue-specific considerations for scaffolding for Tissue engineering (TE) purposes are herein highlighted and discussed in depth. The newest procedures focusing on the 3D behavior and multi-cellular interactions of native tissues for further use for in vitro model processing are also outlined. Completed and ongoing preclinical research trials for TE applications using scaffolds and hydrogels, challenges, and future prospects of research in the regenerative medicine field are also presented.

Synthesis and characterizations of alginate-α-tricalcium phosphate microparticle hybrid film with flexibility and high mechanical property as a biomaterial

A biocompatible hybrid film has been fabricated using alginate (Alg), α-tricalcium phosphate (α-TCP) microparticle and calcium chloride through ionic crosslinking as a biomaterial. The 'screeding method' (like a concrete finishing process) has been employed to develop the Alg-α-TCP film. For this method, the Alg/α-TCP blend has been prepared using an ultra-sonicator and then put on a glass slide. After that, the excess volume of blend has been cut off by skidding another slide along with the surface of the blend to achieve proper grade and flatness. The mechanical strength and flexibility of the film (Alg-α-TCP) has been controlled by changing its compositions. The crosslinking phenomenon has been confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), ¹³C nuclear magnetic resonance (NMR), x-ray diffraction and thermogravimetric analyses. The ATR-FTIR and ¹³C NMR analysis results suggest that carboxylate groups of the alginate are ionically cross-linked with Ca²⁺ ions, while the α-TCP particles reside in the network by physical interaction. The micro-fatigue test results imply high tensile strength (up to 257 MPa) and flexibility (up to 13% elongation) of the Alg-α-TCP hybrid films. The SEM analysis suggests the α-TCP particles are homogeneously distributed on the surface of Alg-α-TCP films, whereas cross-sectional images confirmed the presence of α-TCP in the cross-linked network. TGA results demonstrated that thermal stability of the hybrid film was enhanced due to ionic crosslinking and interfacial interaction between alginate and α-TCP. The incorporation of α-TCP particles diminished the swelling ratio of the hybrid film. The in vitro bone cell (MC3T3) culture and cytotoxicity tests showed that the hybrid film is biocompatible. The hybrid film releases bovine serum albumin and dimethyloxaloylglycine in a controlled way at pH 7 and 7.4, and 37 °C. Overall, the biocompatible Alg-α-TCP hybrid film with excellent mechanical strength and flexibility could be applied as an interfacial film in tissue engineering.