Creating Cartilage in Tissue-Engineered Chamber Using Platelet-Rich Plasma Without Cell Culture

An experimental investigation into the correlation between the diameter of reimplanted cartilage blocks and efficacy of cartilage regeneration after auricular reconstruction

Preventing thoracic deformities during auricular reconstruction is a challenge for surgeons who utilize multiple costal cartilage grafts to fabricate a 3-dimensional framework. Reimplantation of cartilage blocks reduces thoracic deformities, but there is no consensus on how to maximize the effectiveness of reimplantation. We aimed to investigate the correlation between the block diameter and the efficacy of cartilage regeneration at the donor site in a rabbit model. Seventy-two rabbits were randomly placed into 6 groups: those with reimplanted cartilage blocks with a diameter of (1) 0.7 mm, (2) 0.6 mm, (3) 0.5 mm, (4) 0.4 mm, (5) 0.3 mm, and (6) the control group. Cartilage blocks of various diameters were shredded and returned to the perichondrial pocket at the donor site. The efficacy of promoting biomechanical strength, cartilage tissue growth, activation of chondrocyte proliferation, and stimulation of cartilage-specific extracellular matrix secretion was assessed. The diameter of the implanted cartilage block was a highly correlated factor during regeneration. Smaller diameters with appropriate interstitial spaces between blocks promoted better cartilage tissue growth, chondrocyte proliferation, and extracellular matrix secretion. According to our findings, 0.4 mm is the maximum diameter for achieving the best regeneration performance (range, 0.3-0.7 mm).

Genetically engineered chondrocytes overexpressing elastin improve cell retention and chondrogenesis in a three-dimensional GelMA culture system

Elastic cartilage possesses many elastic fibers and has a high degree of elasticity. However, insufficient elastic fiber production remains unsolved in elastic cartilage tissue engineering. Exogenous elastin is difficult to degrade and violates cell proliferation and migration during cartilage regeneration. Moreover, exogenous elastic fibers are difficult to assemble with endogenous extracellular matrix components. We produced genetically engineered chondrocytes overexpressing elastin to boost endogenous elastic fiber production. After identifying that genetic manipulation hardly impacted the cell viability and chondrogenesis of chondrocytes, we co-cultured genetically engineered chondrocytes with untreated chondrocytes in a three-dimensional gelatin methacryloyl (GelMA) system. In vitro study showed that the co-culture system produced more elastic fibers and increased cell retention, resulting in strengthened mechanics than the control system with untreated chondrocytes. Moreover, in vivo implantation revealed that the co-culture GelMA system greatly resisted host tissue invasion by promoting elastic fiber production and cartilage tissue regeneration compared with the control system. In summary, our study indicated that genetically engineered chondrocytes overexpressing elastin are efficient and safe for promoting elastic fiber production and cartilage regeneration in elastic cartilage tissue engineering.

Platelet-rich plasma promotes peripheral nerve regeneration after sciatic nerve injury

The effect of platelet-rich plasma on nerve regeneration remains controversial. In this study, we established a rabbit model of sciatic nerve small-gap defects with preserved epineurium and then filled the gaps with platelet-rich plasma. Twenty-eight rabbits were divided into the following groups (7 rabbits/group): model, low-concentration PRP (2.5–3.5-fold concentration of whole blood platelets), medium-concentration PRP (4.5–6.5-fold concentration of whole blood platelets), and high-concentration PRP (7.5–8.5-fold concentration of whole blood platelets). Electrophysiological and histomorphometrical assessments and proteomics analysis were used to evaluate regeneration of the sciatic nerve. Our results showed that platelet-rich plasma containing 4.5–6.5- and 7.5–8.5-fold concentrations of whole blood platelets promoted repair of sciatic nerve injury. Proteomics analysis was performed to investigate the possible mechanism by which platelet-rich plasma promoted nerve regeneration. Proteomics analysis showed that after sciatic nerve injury, platelet-rich plasma increased the expression of integrin subunit β-8 (ITGB8), which participates in angiogenesis, and differentially expressed proteins were mainly enriched in focal adhesion pathways. Additionally, two key proteins, ribosomal protein S27a (RSP27a) and ubiquilin 1 (UBQLN1), which were selected after protein-protein interaction analysis, are involved in the regulation of ubiquitin levels in vivo. These data suggest that platelet-rich plasma promotes peripheral nerve regeneration after sciatic nerve injury by affecting angiogenesis and intracellular ubiquitin levels.