2022 Issue 4 (Available Online: 2022-12-28)

    Celebrating the 2nd anniversary of Biomaterials Translational
    Zhidao Xia, Qian Wang
    2022, 3(4):  235-236.  doi:10.12336/biomatertransl.2022.04.002
    Abstract ( 153 )   HTML ( 25)   PDF (97KB) ( 159 )  
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    Engineered exosomes for future gene-editing therapy
    Haoyu Guo, Xin Huang
    2022, 3(4):  240-242.  doi:10.12336/biomatertransl.2022.04.003
    Abstract ( 125 )   HTML ( 20)   PDF (311KB) ( 274 )  
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    Elena Giusto, Gordon Blunn, Roberta Ferro de Godoy, Chaozong Liu, Catherine Pendegrass
    2022, 3(4):  243-249.  doi:10.12336/biomatertransl.2022.04.004
    The current osseointegrated transcutaneous implant design has a high rate of infection and soft tissue downgrowth. A three-dimensional additive layer manufacturing (3D ALM) flange design has been compared in-vivo to a bi-dimensional one, resulting in an improvement of soft tissue adhesion and blood vessel formation.
    Abstract ( 158 )   HTML ( 19)   PDF (1018KB) ( 289 )  
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    Osseointegrated transcutaneous implants could provide an alternative and improved means of attaching artificial limbs for amputees, however epithelial down growth, inflammation, and infections are common failure modalities associated with their use. To overcome these problems, a tight seal associated with the epidermal and dermal adhesion to the implant is crucial. This could be achieved with specific biomaterials (that mimic the surrounding tissue), or a tissue–specific design to enhance the proliferation and attachment of dermal fibroblasts and keratinocytes. The intraosseous transcutaneous amputation prosthesis is a new device with a pylon and a flange, which is specifically designed for optimising soft tissue attachment. Previously the flange has been fabricated using traditional machining techniques, however, the advent of additive layer manufacturing (ALM) has enabled 3–dimensional porous flanges with specific pore sizes to be used to optimise soft tissue integration and reduce failure of osseointegrated transcutaneous implants. The study aimed to investigate the effect of ALM–manufactured porous flanges on soft tissue ingrowth and attachment in an in vivo ovine model that replicates an osseointegrated percutaneous implant. At 12 and 24 weeks, epithelial downgrowth, dermal attachment and revascularisation into ALM–manufactured flanges with three different pore sizes were compared with machined controls where the pores were made using conventional drilling. The pore sizes of the ALM flanges were 700, 1000 and 1250 μm. We hypothesised that ALM porous flanges would reduce downgrowth, improve soft tissue integration and revascularisation compared with machined controls. The results supported our hypothesis with significantly greater soft tissue integration and revascularisation in ALM porous flanges compared with machined controls.

    Jingyu Fan, Elizabeth Pung, Yuan Lin, Qian Wang
    2022, 3(4):  250-263.  doi:10.12336/biomatertransl.2022.04.005
    Two main strategies could be applied in fabrication of hydrogen sulfide (H2S)-releasing biomaterials, namely, through physical incorporation or chemical conjugation, based on different needs and various environment in treatment, leading to desired H2S-releasing profiles and corresponding material properties for different applications.
    Abstract ( 293 )   HTML ( 27)   PDF (940KB) ( 888 )  
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    Hydrogen sulfide (H2S) has been reported as an endogenous gasotransmitter that contributes to the modulation of a myriad of biological signalling pathways, which includes maintaining homeostasis in living organisms at physiological concentrations, controlling protein sulfhydration and persulfidation for signalling processes, mediating neurodegeneration, and regulating inflammation and innate immunity, etc. As a result, researchers are actively exploring effective approaches to evaluate the properties and the distribution of H2S in vivo. Furthermore, the regulation of the physiological conditions of H2S in vivo introduces the opportunity to further study the molecular mechanisms by which H2S regulates cellular functions. In recent years, many H2S–releasing compounds and biomaterials that can deliver H2S to various body systems have been developed to provide sustained and stable H2S delivery. Additionally, various designs of these H2S–releasing biomaterials have been proposed to aid in the normal conduction of physiological processes, such as cardioprotection and wound healing, by modulating different signalling pathways and cell functionalities. Using biomaterials as a platform to control the delivery of H2S introduces the opportunity to fine tune the physiological concentration of H2S in vivo, a key to many therapeutic applications. In this review, we highlight recent research works concerning the development and application of H2S–releasing biomaterials with a special emphasis to different release triggering conditions in in vivo studies. We believe that the further exploration of the molecular mechanisms underlying H2S donors and their function when incorporated with various biomaterials will potentially help us understand the pathophysiological mechanisms of different diseases and assist the development of H2S–based therapies.

    Yi Wang, Yangyang Chen, Yulong Wei
    2022, 3(4):  264-279.  doi:10.12336/biomatertransl.2022.04.006
    Understanding the characteristics of various osteochondral defect (OCD) models is critical for the study of biomaterial-assisted osteochondral repair. This review aims to elaborate the advantages, the limitations, the surgical procedures, and the novel biomaterial applications that promote OCD repair in different species.
    Abstract ( 310 )   HTML ( 19)   PDF (435KB) ( 662 )  
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    Clinical therapeutics for the regeneration of osteochondral defects (OCD) in the early stages of osteoarthritis remain an enormous challenge in orthopaedics. For in-depth studies of tissue engineering and regenerative medicine in terms of OCD treatment, the utility of an optimal OCD animal model is crucial for assessing the effects of implanted biomaterials on the repair of damaged osteochondral tissues. Currently, the most frequently used in vivo animal models for OCD regeneration include mice, rats, rabbits, dogs, pigs, goats, sheep, horses and nonhuman primates. However, there is no single “gold standard” animal model to accurately recapitulate human disease in all aspects, thus understanding the benefits and limitations of each animal model is critical for selecting the most suitable one. In this review, we aim to elaborate the complex pathological changes in osteoarthritic joints and to summarise the advantages and limitations of OCD animal models utilised for biomaterial testing along with the methodology of outcome assessment. Furthermore, we review the surgical procedures of OCD creation in different species, and the novel biomaterials that promote OCD regeneration. Above all, it provides a significant reference for selection of an appropriate animal model for use in preclinical in vivo studies of biomaterial-assisted osteochondral regeneration in osteoarthritic joints.

    Guixin Yuan, Zan Li, Xixi Lin, Na Li, Ren Xu
    2022, 3(4):  280-294.  doi:10.12336/biomatertransl.2022.04.007
    Spatial distributions of skeletal stem cells (SSCs) are currently found in the growth plate, periosteum, and bone marrow of long bones, as well as in craniofacial bones. At present, SSCs can be distinguished by various cell surface markers, and this group of cells mainly contributes to the process of bone regeneration and bone repair. Furthermore, several signalling pathways have also been shown to regulate the SSC niche.
    Abstract ( 310 )   HTML ( 26)   PDF (7147KB) ( 542 )  
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    Tissue–resident stem cells are a group of stem cells distinguished by their capacity for self–renewal and multilineage differentiation capability with tissue specificity. Among these tissue–resident stem cells, skeletal stem cells (SSCs) were discovered in the growth plate region through a combination of cell surface markers and lineage tracing series. With the process of unravelling the anatomical variation of SSCs, researchers were also keen to investigate the developmental diversity outside the long bones, including in the sutures, craniofacial sites, and spinal regions. Recently, fluorescence–activated cell sorting, lineage tracing, and single–cell sequencing have been used to map lineage trajectories by studying SSCs with different spatiotemporal distributions. The SSC niche also plays a pivotal role in regulating SSC fate, such as cell–cell interactions mediated by multiple signalling pathways. This review focuses on discussing the spatial and temporal distribution of SSCs, and broadening our understanding of the diversity and plasticity of SSCs by summarizing the progress of research into SSCs in recent years.