title: Atomic force microscopy reveals age-dependent changes in nanomechanical properties of the extracellular matrix of native human menisci: implications for joint degeneration and osteoarthritis.
abstract: With aging, the menisci become more susceptible to degeneration due to sustained mechanical stress accompanied by age-related changes in the extracellular matrix (ECM). However, the mechanistic relationship between age-related meniscal degeneration and osteoarthritis (OA) development is not yet fully understood. We have examined the nanomechanical properties of the ECM of normal, aged, and degenerated human menisci using atomic force microscopy (AFM). Elasticity maps of the ECM revealed a unique differential qualitative nanomechanical profile of healthy young tissue: prominent unimodal peaks in the elastic moduli distribution in each region (outer, middle, and inner). Healthy aged tissue showed similar regional elasticity but with both unimodal and bimodal distributions that included higher elastic moduli. In contrast, degenerated OA tissue showed the broadest distribution without prominent peaks indicative of substantially increased mechanical heterogeneity in the ECM. AFM analysis reveals distinct regional nanomechanical profiles that underlie aging-dependent tissue degeneration and OA.
  
  
  BACKGROUND
  The authors of this study used atomic force microscopy to determine the nanomechanical properties of the extracellular matrix in normal and degenerated human menisci, as well as in menisci undergoing healthy aging. Comparison of these properties help to understand the relationship between healthy ageing, and age-dependent joint degeneration and osteoarthritis.
authors: Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, USA; Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA, USA; Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, CA, USA.
authors: Jeanie
authors: J
authors: Kwok
authors: Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, CA, USA.
authors: Shawn
authors: S
authors: Grogan
authors: Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
authors: Brian
authors: B
authors: Meckes
authors: Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, USA; Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
authors: Fernando
authors: F
authors: Arce
authors: Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, USA; Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA, USA; Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA. Electronic address: rlal@eng.ucsd.edu.
authors: Ratnesh
authors: R
authors: Lal
authors: Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, CA, USA. Electronic address: DLima.Darryl@scrippshealth.org.
authors: Darryl
authors: D
authors: D'Lima
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D005109:Extracellular Matrix / Q000378:metabolism*; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis*; D018625:Microscopy, Atomic Force / Q000379:methods*; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis*; D013314:Stress, Mechanical; D055815:Young Adult
keywords: Atomic force microscopy; Meniscus; Nanomechanics; Osteoarthritis