The temporomandibular joint (TMJ) is a ginglymoarthrodial joint that comprises a fibrocartilaginous disc that is highly predisposed to suffer from trauma or degenerative events, leading to disorders in the condyle–disc complex. The use of decellularized tissues has attracted interest in the tissue engineering (TE) field as an intact extracellular matrix can be obtained [
1]. To this end, the ovine model was the first choice for a TMJ TE approach as they are easy to obtain, inexpensive and present an easily accessible surgical site [
2]. When biological materials are used, their conservation should be taken into consideration, as sometimes it is not possible to test them immediately after extraction. With this, the present study aims to characterise the ovine disc, and determine its maximum freezing-time storage without alterations in its morphological and compression properties and biochemical composition. For this, two storage conditions were tested: (i) freezing at −20 °C in phosphate buffered saline (PBS) solution and thaw at 4 °C (PBS + 4 °C) and (ii) wrapping the discs in PBS embedded gauze and freezing at −20 °C followed by thaw at room temperature (RT) in PBS (Gauze + RT). Moreover, different time intervals were assessed: 1, 7 and 14 days. Results showed that the native disc presented a thickness of 1.62 ± 0.674 mm, weighted 0.385 ± 0.029 g and had a compressive modulus of 2.36 ± 0.072 MPa. Regarding biochemical composition, collagen content was higher in the central zone, whereas glycosaminoglycans were higher in the lateral and posterior zone. After performing both storage methods, morphological characteristics were minimally altered, but the biochemical content was significantly affected. After the 14-day experiments, there was an increase of about 30% in the compression modulus for Gauze + RT when compared to the fresh native disc, while for the PBS + 4 °C no changes were observed. This study determined that freezing the ovine discs may lead to changes in the native properties, indicating that when it is necessary to store them, these changes should be taken into consideration in future studies.
Author Contributions
Conceptualization, D.T., C.R.C.C., N.A. and C.M.; methodology, D.T. and C.M.; writing—original draft preparation, D.T.; writing—review and editing, C.R.C.C., N.A. and C.M.; supervision, N.A. and C.M.; funding acquisition, N.A. and C.M.. All authors have read and agreed to the published version of the manuscript.
Funding
This work was funded by the Fundação para a Ciência e a Tecnologia FCT/MCTES (PIDDAC) and Centro2020 through the following Projects: UIDB/04044/2020; UIDP/04044/2020; SFRH/BD/145292/2019; Associate Laboratory ARISE LA/P/0112/2020; PAMI-ROTEIRO/0328/2013 (Nº 022158) and Biodiscus (CENTRO-01-0247-FEDER-039969).
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Trindade, D.; Cordeiro, R.; José, H.C.; Ângelo, D.F.; Alves, N.; Moura, C. Biological Treatments for Temporomandibular Joint Disc Disorders: Strategies in Tissue Engineering. Biomolecules 2021, 11, 933. [Google Scholar] [CrossRef] [PubMed]
- Almarza, A.J.; Brown, B.N.; Arzi, B.; Ângelo, D.F.; Chung, W.; Badylak, S.F.; Detamore, M. Preclinical Animal Models for Temporomandibular Joint Tissue Engineering. Tissue Eng. Part B Rev. 2018, 24, 171–178. [Google Scholar] [CrossRef] [PubMed]
| Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).