title: Biomechanical and cellular segmental characterization of human meniscus: building the basis for Tissue Engineering therapies.
abstract: OBJECTIVE
  To overcome current limitations of Tissue Engineering (TE) strategies, deeper comprehension on meniscus biology is required. This study aims to combine biomechanical segmental analysis of fresh human meniscus tissues and its correlation with architectural and cellular characterization.
  
  
  METHODS
  Morphologically intact menisci, from 44 live donors were studied after division into three radial segments. Dynamic mechanical analysis (DMA) was performed at physiological-like conditions. Micro-computed tomography (CT) analysis of freeze-dried samples assessed micro-structure. Flow cytometry, histology and histomorphometry were used for cellular study and quantification.
  
  
  RESULTS
  Anterior segments present significantly higher damping properties. Mid body fresh medial meniscus presents higher values of E' compared to lateral. Cyclic loads influence the viscoelastic behavior of menisci. By increasing the frequency leads to an increase in stiffness. Conversely, with increasing frequencies, the capacity to dissipate energy and damping properties initially decrease and then rise again. Age and gender directly correlate with higher E' and tan δ. Micro-CT analysis revealed that mean porosity was 55.5 (21.2-89.8)% and 64.7 (47.7-81.8)% for freeze-dried lateral and medial meniscus, respectively. Predominant cells are positive for CD44, CD73, CD90 and CD105, and lack CD31, CD34 and CD45 (present in smaller populations). Histomorphometry revealed that cellularity decreases from vascular zone 1 to zone 3. Anterior segments of lateral and medial meniscus have inferior cellularity as compared to mid body and posterior ones.
  
  
  CONCLUSIONS
  Menisci are not uniform structures. Anterior segments have lower cellularity and higher damping. Cyclic loads influence viscoelastic characteristics. Future TE therapies should consider segmental architecture, cellularity and biomechanics of fresh tissue.
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal; Clínica Espregueira-Mendes F.C. Porto Stadium - FIFA Medical Centre of Excellence, Portugal; Orthopedic Department Centro Hospitalar Póvoa de Varzim - Vila do Conde, Portugal. Electronic address: helderduartepereira@gmail.com.
authors.forename: H
authors.initials: H
authors.lastname: Pereira
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal.
authors.forename: S G
authors.initials: SG
authors.lastname: Caridade
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal.
authors.forename: A M
authors.initials: AM
authors.lastname: Frias
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Silva-Correia
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal.
authors.forename: D R
authors.initials: DR
authors.lastname: Pereira
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal.
authors.forename: I F
authors.initials: IF
authors.lastname: Cengiz
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal.
authors.forename: J F
authors.initials: JF
authors.lastname: Mano
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal. Electronic address: miguel.oliveira@dep.uminho.pt.
authors.forename: J M
authors.initials: JM
authors.lastname: Oliveira
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal; Clínica Espregueira-Mendes F.C. Porto Stadium - FIFA Medical Centre of Excellence, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Espregueira-Mendes
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, Univ. Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909, Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associated Laboratory, Portugal.
authors.forename: R L
authors.initials: RL
authors.lastname: Reis
mesh_terms: D000293:Adolescent; D000368:Aged; D000818:Animals; D001696:Biomechanical Phenomena; D002469:Cell Separation / Q000379:methods; D004548:Elasticity; D005434:Flow Cytometry; D006801:Humans; D008592:Menisci, Tibial / Q000166:cytology / Q000502:physiology*; D008875:Middle Aged; D016062:Porosity; D013045:Species Specificity; D023822:Tissue Engineering / Q000379:methods*; D014783:Viscosity; D016474:Weight-Bearing / Q000502:physiology; D055114:X-Ray Microtomography; D055815:Young Adult
keywords: DMA (dynamic mechanical analysis); Flow cytometry; Histomorphometry; Meniscus; Micro-computed tomography; Tissue engineering