Chronic tympanic membrane perforation repair with a collagen-based scaffold: An in vivo model.

OBJECTIVE: The aim of this study was to assess the in vivo efficacy of a novel regenerative collagen-based scaffold developed by the Royal College of Surgeons in Ireland in a chronic tympanic membrane perforation (TMP) using a chinchilla model. METHODS: Bilateral TMPs were induced in 17 mixed gender chinchillas using tympanic membrane resection followed by a mixture of topical Mitomycin C and dexamethasone for 3 days. These were monitored with weekly otoscopy for 8 weeks. Animals were excluded if signs of infection developed in the follow up period (n = 8). At 8 weeks, intervention began and 18 TMPs were assigned to either treatment with the collagen-based scaffold (treated group) or spontaneous healing (control group). Animals were euthanized 6 weeks post-intervention. Otoscopic imaging and auditory brain response (ABR) were conducted at baseline, 8 weeks post-TMP induction and 6 weeks post-intervention. All TMPs were then evaluated at 6 weeks post-intervention and bullae underwent histologic evaluation. RESULTS: At 6 weeks post-intervention, otoscopic imaging demonstrated various degrees of healing in the treated ears. The treated group was noted to have an increased rate of healing when compared to the control group. Histologic evaluation demonstrated a variation in the degree of perforation healing within groups, with some animals in the treated group showing high levels of perforation healing. At 8 weeks after the TMP procedure, most of the animals had worsened hearing response. At 6-week post the collagen-based scaffold treatment, about 50 % (4/8) of the treated ears had improved in hearing response as compared to those of non-treated ears. CONCLUSION: Given the initial histologic evidence of partial healing in scaffold-treated ears, the post-intervention period should be extended to monitor the potential for complete healing. Given the overall positive findings related to healing with the scaffold-treated ears, this material warrants further investigation.

Platelet-rich plasma releasate differently stimulates cellular commitment toward the chondrogenic lineage according to concentration.

Platelet-rich plasma has been used to treat articular cartilage defects, with the expectations of anabolic and anti-inflammatory effects. However, its role on cellular chondrogenic or fibrogenic commitment is still a controversy. Herein, the role of platelet-rich plasma releasate, the product obtained following platelet-rich plasma activation, on cellular commitment toward the chondrogenic lineage was evaluated in vitro. Human nasoseptal chondrogenic cells and human bone marrow mesenchymal stromal cells were used as cell types already committed to the chondrogenic lineage and undifferentiated cells, respectively, as different concentrations of platelet-rich plasma releasate were tested in comparison to commonly used fetal bovine serum. Low concentration of platelet-rich plasma releasate (2.5%) presented similar effects on cellular growth compared to 10% fetal bovine serum, for both cell types. In a three-dimensional culture system, platelet-rich plasma releasate alone did not induce full nasoseptal chondrogenic cells cartilage-like pellet formation. Nonetheless, platelet-rich plasma releasate played a significant role on cell commitment as high-passage nasoseptal chondrogenic cells only originated cartilage-like pellets when expanded in the presence of platelet-rich plasma releasate rather than fetal bovine serum. Histological analyses and measurements of pellet area demonstrated that even low concentrations of platelet-rich plasma releasate were enough to prevent nasoseptal chondrogenic cells from losing their chondrogenic potential due to in vitro expansion thereby promoting their recommitment. Low concentration of platelet-rich plasma releasate supplemented in chondrogenic medium also increased the chondrogenic potential of mesenchymal stromal cells seeded on collagen-hyaluronic acid scaffolds, as observed by an increase in chondrogenic-related gene expression, sulfated glycosaminoglycan production, and compressive modulus following in vitro culture. On the contrary, higher concentration of platelet-rich plasma releasate (10%) hampered some of these features. In conclusion, platelet-rich plasma releasate was able to prevent cellular chondrogenic capacity loss, inducing regain of their phenotype, and modulate cell commitment. Our data support the hypothesis of platelet-rich plasma chondrogenic potential, allowing fetal bovine serum substitution for platelet-rich plasma releasate at specific concentrations in culture medium when chondrogenic commitment is desired on specific cell types and moments of culture.