Periodic Reporting for period 4 - ReCaP (Regeneration of Articular Cartilage using Advanced Biomaterials and Printing Technology)
Periodo di rendicontazione: 2023-02-01 al 2024-07-31
Damaged articular cartilage joints (e.g. knee) are associated with loss of function and joint degeneration which can lead to osteoarthritis (OA) and the need for total joint replacement. For the treatment of small cartilage defects, conventional therapies e.g. microfracture and osteochondral autograft transplantation are used, but with limited success. An advanced biomaterial capable of restoring healthy joint function remains something of a ‘Holy Grail’. Developing a biomaterial-based solution for the repair of large joint damage presents a particularly complex challenge due to: (i) the complex zonal structure of the tissue (i.e. articular cartilage on top, an intermediate calcified cartilage layer, and underlying subchondral bone); (ii) difficulty in keeping a biomaterial in place in the joint; and (iii) challenges in directing stem cells to promote the formation of stable cartilage. Building on a wealth of experience in the area, we propose a solution. ReCaP will initially overcome the problems with traditional biomaterials approaches by utilising recent advances in the area of advanced manufacturing and 3D-printing to develop a 3D-printed multi-layered scaffold with pore architecture, mechanical properties and bioactive composition tailored to regenerate articular cartilage, intermediate calcified cartilage and subchondral bone. Following this, and building on internationally recognised pioneering research in the applicant’s lab on scaffold-mediated nanomedicine delivery, this system will be functionalised for the controlled non-viral delivery of nucleic acids (including plasmid DNA and microRNAs) to direct host stem cells to produce stable hyaline cartilage at the joint surface and encourage the rapid formation of vascularised bone in the subchondral region. A new paradigm-shifting surgical procedure will then be applied to allow this system to be anchored to the joint surface while directing host cell infiltration and tissue repair, thus promoting the restoration of even large regions of the damaged joint through a joint surfacing approach. The proposed ReCaP platform is thus a paradigm shifting disruptive technology that will revolutionise the way joint injuries are treated.
WP1: A novel 3D printing process utilising fused deposition modelling (FDM) or melt electrowriting (MEW) was developed, enabling us to develop a single PCL structure with 3 finely tailored designs - fabricated in-house. This 3D Printed Multi-Layered (PML) scaffold enabled cell infiltration and proliferation, directing mesenchymal stem cells (MSCs) chondrogenesis and osteogenesis in a layer specific manner. The PML scaffold promoted significant osteochondral repair, guided by host cells, when implanted into load-bearing osteochondral defects in goats.
WP2: Successful gene activation of reinforced (and non-reinforced) collagen-based 3D matrices (from WP1) with nanoparticles (NPs) that are internalized by the stem cells which migrate into the scaffold. We successfully incorporated the gene-complexed NPs into previously fabricated collagen-based matrices and produced a novel ‘off-the-shelf’ gene activated bio-ink. We investigated a series of multi-functional therapeutic molecules. The most promising gene activated scaffold platform (GASP) to enhance cartilage repair was tested in vivo in a rat osteochondral model. We are still assessing some outputs from this WP in an ongoing in vivo study in RCSI so further publications are likely to accrue in due course.
WP3: Outputs from WP1 and WP2 were combined to produce a technology platform capable of resurfacing large areas of the damaged articular joint. A sheet of a single superficial chondral layer of the 3D printed scaffold was produced. The resulting chondral sheet retained mechanical properties of the PCL structure while incorporating the microstructural and biochemical features of our regenerative matrix, which promoted MSC chondrogenic differentiation and sulphated glycosaminoglycan rich matrix deposition. This demonstrates the PCL structure has enhanced the scaffold’s chondrogenic capacity. We designed an innovative fixation method to attach the implant to adjacent bone tissue, which facilitated repair of large articular cartilage defects in a goat medial femoral condyle, providing an alternative strategy to those available in the clinic. The developed chondral sheet (WP3) was advanced to a reinforced GASP sheet to enhance cartilage-like formation while retaining physical and biochemical features of native articular cartilage. This demonstrates that the incorporation of therapeutic genes into a scaffold platform designed specifically for cartilage repair is a promising treatment/surgical approach for repair of large scale articular damage.
WP2: Successful gene activation of reinforced (and non-reinforced) collagen-based 3D matrices (from WP1) with nanoparticles (NPs) that are internalized by the stem cells which migrate into the scaffold. We successfully incorporated the gene-complexed NPs into previously fabricated collagen-based matrices and produced a novel ‘off-the-shelf’ gene activated bio-ink. We investigated a series of multi-functional therapeutic molecules. The most promising gene activated scaffold platform (GASP) to enhance cartilage repair was tested in vivo in a rat osteochondral model. We are still assessing some outputs from this WP in an ongoing in vivo study in RCSI so further publications are likely to accrue in due course.
WP3: Outputs from WP1 and WP2 were combined to produce a technology platform capable of resurfacing large areas of the damaged articular joint. A sheet of a single superficial chondral layer of the 3D printed scaffold was produced. The resulting chondral sheet retained mechanical properties of the PCL structure while incorporating the microstructural and biochemical features of our regenerative matrix, which promoted MSC chondrogenic differentiation and sulphated glycosaminoglycan rich matrix deposition. This demonstrates the PCL structure has enhanced the scaffold’s chondrogenic capacity. We designed an innovative fixation method to attach the implant to adjacent bone tissue, which facilitated repair of large articular cartilage defects in a goat medial femoral condyle, providing an alternative strategy to those available in the clinic. The developed chondral sheet (WP3) was advanced to a reinforced GASP sheet to enhance cartilage-like formation while retaining physical and biochemical features of native articular cartilage. This demonstrates that the incorporation of therapeutic genes into a scaffold platform designed specifically for cartilage repair is a promising treatment/surgical approach for repair of large scale articular damage.
We have broadened the project scope, moving beyond large articular tissue defects into treatments for early stage OA and controlling effects of chronic joint inflammation. This has led to follow on research funding for the group. Design and fabrication of multilayer PML scaffolds (WP1) involved an innovative 3D printing technique which has applications beyond bone and cartilage repair. An example of the wide applicability of our technology is its use in the development of a new reinforced scaffold with dual capacity for bone regeneration while having antimicrobial potential, for use in repairing bone defects caused by infections (i.e. osteomyelitis). The fabrication process shows potential for developing scaffolds for meniscus injuries and for reinforcing matrices for non-musculoskeletal tissue repair such as urinary, ocular and nervous systems. Development of the novel gene-activated scaffold platforms (WP2) was possibly the most technically challenging aspect of ReCaP. To solve the complex challenges presented (described in detail in other sections of the report), we investigated the suitability of several non-viral vectors designed in-house and obtained via scientific collaborations. Despite selection of GAG-binding enhanced transduction (GET) as the optimal vector for ReCaP, other vectors we investigated have shown potential for other applications, thus expanding the scope of the ReCaP research beyond osteochondral repair. As a result, the gene activated scaffold concept has now been applied to other tissues for which treatment options are limited such as spinal cord and chronic wounds. For example, two successful follow-on grants have seen projects commence in the treatment of epidermolysis bullosa while an ERC PoC application has been approved for funding focusing on spinal cord repair. An innovative biomaterial fixation method was designed to improve attachment of implants to adjacent bone tissue (WP3). This facilitated repair of large articular cartilage defects in goats. The results demonstrate a simple and effective chondral biomaterial fixation technique which could open many avenues of research for application with other engineered cartilage constructs.