The evaluation of gradient scaffolds for osteochondral regeneration
The goal of this project is to combine the osteochondral platform of LifeTec Group with the ultra-high field Magnetic Resonance Imaging at Scannexus to evaluate the regenerative capacity of gradient scaffolds for the treatment of osteochondral defects developed at University Maastricht. This public-private collaboration combines the research at University Maastricht with the available technologies at Scannexus and LifeTec Group B.V.
Articular cartilage injuries are common in orthopedic practice. Cartilage possesses very limited capacity for self-repair and therefore, cartilage defects do not heal spontaneously and are likely to progress into osteoarthritis if left untreated. Osteoarthritis affects millions of people worldwide. New and efficient treatment strategies are needed to treat osteochondral defects to prevent deterioration into osteoarthritis.
Ideally, the treatment of cartilage defects would result in regenerated tissue which resembles the native osteochondral tissue in structure, composition and function. In this project, scaffolds that contain gradients in analogy to gradients found in native osteochondral tissue were evaluated in an ex vivo platform, which mimics the in vivo tissue environment, without using animal experiments.
In the first phase of this project: 1) The osteochondral platform of LifeTec was taken into use in Maastricht, the optimal size of plugs and defects were defined. 2) The scaffolds as a regenerative treatment for cartilage defects with and without gradient were bioprinted at MERLN and 3) Sequences and post-processing steps to image and quantify the cartilage quality of osteochondral plugs were developed at Scannexus (Figure 1).
In the second phase, plugs containing scaffolds with different types of gradient were tested in the ex vivo osteochondral platform and imaged using 9.4T MRI to measure cartilage quality. Differences between conditions were observed in the tissue surrounding the defect, but not inside the scaffolds. Standardization is needed to decrease the amount of variation between plugs in the same condition.
Figure 1: Example of the MR images of an osteochondral plug using the three sequences that were developed on 7T MR to quantify cartilage quality. A: morphological image showing the anatomy. B: morphological image with the amount of glycosaminoglycans overlayed in the cartilage region, measured in Magnetization Transfer Ratio (MTR), high values indicate good cartilage quality. C: morphological image with the integrity of the collagen network overlayed in the cartilage region, measured in T2map relaxation time, the alternating orientation of collagen fibers in healthy cartilage gives rise to three different layers in signal as depicted in the image.
