###### Abstract  
Osteochondral scaffold technology has emerged as a promising therapy for repairing osteochondral defects. Recent research suggests that seeding osteochondral scaffolds with bone marrow concentrate (BMC) may enhance tissue regeneration. To examine this hypothesis, this study examined subchondral bone regeneration in scaffolds with and without BMC. Ovine softle condyle models were used for the in vivo study. Two scaffold systems (8 mm diameter and 10 mm thick) with and without BMC were implanted into the femoral condyle, and the tissues were retrieved after six months. The retrieved femoral condyles (with scaffold in) were examined using micro-computed tomography scans (micro-CT), and the micro-CT data were further analysed by ImageJ with respect to trabecular thickness, bone volume to total volume ratio (BV/TV) ratio, and degree of anisotropy of bone. Statistical analysis compared bone regeneration between scaffold groups and sub-set regions. These results were mostly insignificant (\(p<0.05\)), with the exception of bone volume to total volume ratio when comparing scaffold composition and sub-set region. Additional trends in the data were observed. These results suggest that the scaffold composition and addition of BMC did not significantly affect bone regeneration in osteochondral defects after six months. However, this research provides data which may guide the development of future treatments.  
bone regeneration; scaffold; tissue engineering; micro-computed tomography; regenerative medicine; bone tissue-material interaction +
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Studies suggest that the use of BMC increases the quantity and quality of tissues within the osteochondral unit because it promotes both osteogenesis and chondrogenesis. It has also been suggested that BMC enhances joint health and longevity because it contains an amalgamation of allogenic platelets, progenitor cells, lymphocytes, and growth actions in addition to stem cells. This method also eliminates the timeliness and high cost affiliated with the sole use of stem cells [16; 17; 18].  
It is important to study tissue regeneration in OCTE treatments in order to assess success, efficacy, and safety. Methods commonly applied to study regenerated tissues (e.g., histology) are destructive, thus limiting the information extracted from the samples. Imaging methods such as micro-computed tomography (micro-CT) may be used to address this issue. Micro-CT machines scan specimens to create 2D pixel maps in thin slices through an entire object; these can then be used to generate 3D models for digital data collection [19]. This is an attractive method of analysis because it is non-destructive, detailed, and efficient. Research has also shown that micro-CT data can be successfully utilised for analysing bone and cartilage structure, the quantity of tissue growth, and scaffold structure whilst also rendering results consistent with traditional techniques [19; 20; 21; 22].  
In this study, a novel osteochondral scaffold based on a composite matrix of titanium, polylactic acid (PLA), and collagen-polylactic co glycolic acid (PLGA) was developed. The scaffolds were evaluated using ovine stifle condyle models. The bone formation within the bone compartment of the scaffolds was examined using micro-CT. The present study analysed the performance of this scaffold with and without BMC cells to determine if the inclusion of BMC contributed to the significant increase in bone regeneration. Subchondral bone was chosen as the focal tissue because it supports the articular cartilage, endures the biomechanical forces within the joint, and is the main hub for active tissue remodelling within the osteochondral unit. Micro-CT images were further analysed using ImageJ to determine trabecular thickness (TbTh), bone volume to total volume ratio (BV/TV), and the degree of anisotropy (DA) within the tested samples, offering insight into the regeneration of the subchondral bone.