Long-term Evaluation of Meniscal Tissue Formation in 3-dimensional–Printed Scaffolds With Sequential Release of Connective Tissue Growth Factor and TGF-β3 in an Ovine Model

Abstract

Background: Artificial meniscal scaffolds are being developed to prevent development of osteoarthritis after meniscectomy. Previously, it was reported that 3-dimensional (3D) anatomic scaffolds loaded with connective tissue growth factor (CTGF) and transforming growth factor β3 (TGF-β3) achieved meniscal regeneration in an ovine model. This was a relatively short-term study (3 months postoperative), and outcome analyses did not include magnetic resonance imaging (MRI). Purpose: To evaluate long-term outcome of meniscal replacement with growth factor–laden poly-ε-caprolactone (PCL) scaffolds. Study Design: Controlled laboratory study. Methods: Anatomically shaped ovine meniscal scaffolds were fabricated from PCL with a 3D printer based on MRI data. Skeletally mature sheep (N = 34) were randomly allocated to 3 groups: scaffold without growth factor (0-µg group), scaffold with CTGF microspheres (µS) (5 µg) + TGF-β3 µS (5 µg) (5-µg group), and scaffold with CTGF µS (10 µg) + TGF-β3 µS (10 µg) (10-µg group). Unilateral medial meniscal replacement was performed. Animals were euthanized at 6 or 12 months. Regenerated meniscus, articular cartilage status, and synovial reaction were evaluated quantitatively with gross inspection, histology, and MRI. Kruskal-Wallis and Dunn tests were used to compare the 3 groups. Results: Remnants of the PCL scaffold were evident in the 6-month specimens and were decreased but still present at 12 months in most animals. There were no significant differences among groups in gross inspection, histology, or MRI for either meniscal regeneration or articular cartilage protection. All experimental groups exhibited articular cartilage degeneration as compared with control (nonoperated). In terms of synovitis, there were no clear differences among groups, suggesting that growth factors did not increase inflammation and fibrosis. MRI revealed that meniscal extrusion was observed in most animals (82.7%). Conclusion: Previously, the combination of CTGF and TGF-β3 was shown to stimulate mesenchymal stem cells into a fibrochondrocyte lineage. CTGF and TGF-β3 did not aggravate synovitis, suggesting no adverse response to the combination of 3D-printed PCL scaffold combined with CTGF and TGF-β3. Further work will be required to improve scaffold fixation to avoid meniscal extrusion. Clinical Relevance: A significant advantage of this technique is the ability to print custom-fit scaffolds from MRI-generated templates. In addition, average-size menisci could be printed and available for off-the-shelf applications. Based on the 1-year duration of the study, the approach appears to be promising for meniscal regeneration in humans.

Biosynthetic scaffolds for partial meniscal loss: A systematic review from animal models to clinical practice

“…Sixteen studies investigated natural scaffolds [ [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] ], 15 synthetic [ [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] , [48] , [49] , [50] , [51] ] and 15 hybrid natural/synthetic [ [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] ] ones ( Fig. 2 ).…”

“…2 ). Some of them were implanted without cells [ [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] ] and some with cells [ [30] , [31] , [32] , [33] , [34] , [35] , [36] , [45] , [46] , [47] , [48] , [49] , [50] , [51] , [63] , [64] , [65] , [66] ]. Twenty-one in vivo studies were conducted in rabbits [ 21 , [23] , [24] , [25] , 28 , 29 , [33] , [34] , [35] , [36] , 39 , 41 , 45 , 46 , [50] , [51] , [52] , [61] , [62] , [63] …”

“…The following cell-free scaffolds were investigated: decellularized meniscus extracellular matrix (DMECM) sponge and DMECM/PCL fiber [ 52 ]; Type I bovine Achilles tendon collagen sponge reinforced with p(DTDDD) fibers [ [53] , [54] , [55] , [56] ]; COLL–HA reinforced with PLLA fibers [ 57 ]; PCL/HA (70/30), augmented with PLA fibers or PET nets [ 58 ]; PGA/HA [ 59 ]; multi layered scaffold, composed by PHBV, HA and strontium ranelate, and durable cellulose fibers from Luffa cylindrical [ 60 ]; PCL (MW = 80 kDa) and PEO (50/50) electrospun nanofibrous and TEC [ 61 ]; PCL (MW = 65000) in which TGFβ3 and CTGF were encapsulated in PLGA μS [ 62 ]. The first scaffold of the aforementioned list induced the formation of a meniscus tissue with higher meniscus-like cells, covering area, regeneration, GAGs, COLL I and COLL II than empty defects.…”

The Meniscus Tear: A Review of Stem Cell Therapies

“…For this reason, research has focused on the application of various growth factors within scaffolds, to meniscal injury models with the hope of an enhanced healing response. Of note, recently transforming growth factor (TGF-β3) and connective tissue growth factor (CTGF) have shown positive results in ovine model meniscal repairs, with the ability to induce cell differentiation towards native zone-specific matrix phenotypes [83,84]. This highlights the key roles of MSCs and growth factors in successful meniscal healing to generate cellular phenotypes resembling that of normal meniscal tissue.…”

The recent advances in scaffolds for integrated periodontal regeneration

“…The abovementioned scaffold biomaterials are mostly biodegradable that means the implanted scaffolds undergo degradation in body as replaced by newly forming tissue. Most of hydrogels degrade relatively fast and synthetic polymers such as PLA, PGA, PLGA and PCL shows slower degradation with some degree of controllability [ [184] , [185] , [186] , [187] , [188] ]. The degradation rate of those biomaterials has been well characterized in vitro but such degradation can be quite different in vivo due to biochemical environment associated with blood supply, inflammation and metabolism [ [184] , [185] , [186] , [187] , [188] ].…”