3D printing of fibre-reinforced cartilaginous templates for the regeneration of osteochondral defects

Articular cartilage and osteochondral tissue engineering techniques: Recent advances and challenges

“…A derivative of collagen by partial hydrolysis with much lower antigenicity Biologically active for cellular interaction, low immunogenicity in comparison to collagen, ease of processing and functionalization Poor mechanical properties, rapid degradation, low thermal stability [ 98 , [114] , [115] , [116] ] Silk fibroin No. The major protein component of natural silk High mechanical strength, low immunogenicity, structural similarity to collagen, morphologic flexibility, good sterilizability Source variability, low biodegradability of the β-sheet crystals [ [117] , [118] , [119] , [120] ] Synthetic polymers Poly(ethylene glycol) (PEG) Poly(ethylene oxide) (PEO) No Good biocompatibility, versatility in processing and functionalization, mechanical adjustability, low immunogenicity Biologically inert for cellular interaction, non-biodegradability [ [121] , [122] , [123] , [124] ] Polylactic acid (PLA) Polyglycolic acid (PGA) Poly(lactic acid-co-glycolic acid) (PLGA) No Good biocompatibility and biodegradability, ease of functionalization, low immunogenicity Low bioactivity, acidic degradation products eliciting inflammatory response [ [125] , [126] , [127] , [128] ] Polycaprolactone (PCL) No Relatively low melting temperature for 3D printing, long-term mechanical stability, ease to manufacture …”

Printing New Bones: From Print-and-Implant Devices to Bioprinted Bone Organ Precursors

“…However, as previously stated, this can lead to cell death and core necrosis due to lack of vascularisation and/or nutrient deficiency [21,107]. Bioprinting strategies have sought to overcome these issues using two distinct techniques (Figure 2A,B): (i) bioprinting and maturing a vascular network prior to implantation [82,[108][109][110][111][112][113][114][115][116][117], such that when implanted the engineered vascular networks can anastomose with the host vasculature [115,116], enabling rapid perfusion of the engineered tissue and (ii) bioprinting an avascular cartilage template primed for endochondral bone formation, which potentially negates the need to pre-vascularise engineered tissues as such constructs are equipped to survive the initially hypoxic defect environment and are capable of executing an endochondral programme to regenerate lost bone [82,118,119].…”

“…Cartilaginous templates generated in vitro using mesenchymal stem/marrow stromal cells (MSCs) have been shown to support vascularisation and bone formation in vivo [118,124], and by leveraging 3D printing strategies it is possible to modulate the architecture of such engineered cartilage grafts to enhance their capacity to regenerate large bone defects [82]. Furthermore, multiple-tool biofabrication can be used to engineer a mechanically reinforced cartilaginous template without negatively impacting its capacity to support the development of a vascularised bone organ in vivo [82,118] or to generate the osseous regions of osteochondral implants targeting the regeneration of synovial joints [119]. Despite the promise of such developmentally inspired bioprinting strategies for bone regeneration, numerous factors need to be optimised before this technique can realise its full potential.…”

Scaffold-Mediated Gene Delivery for Osteochondral Repair

“…Initially, the scaffold should provide a biomechanically strong support, with an adapted porous structure to permit cellular activities, together with an appropriate in vivo degradation rate that is in parallel to the ECM deposition. Combination of biomaterials with advanced technologies [ 78 , 79 , 80 , 81 , 82 , 83 ] has allowed for developing a new generation of 3D scaffolds with adapted features for cartilage and bone repair [ 84 ]. The technique of 3D printing has been also applied to generate osteochondral constructs that may be tailored in the future to match the often irregular osteochondral defects.…”

“…The technique of 3D printing has been also applied to generate osteochondral constructs that may be tailored in the future to match the often irregular osteochondral defects. A recent study engineered biphasic osteochondral constructs from 3D-printed fiber networks that mechanically reinforces alginate hydrogels whilst simultaneously supporting MSC chondrogenesis [ 83 ].…”