Age-Dependent Remodeling in Infrapatellar Fat Pad Adipocytes and Extracellular Matrix: A Comparative Study

Abstract

The infrapatellar fat pad (IFP) is actively involved in knee osteoarthritis (OA). However, a proper description of which developmental modifications occur in the IFP along with age and in absence of joint pathological conditions, is required to adequately describe its actual contribution in OA pathophysiology. Here, two IFP sources were compared: (a) IFP from healthy young patients undergoing anterior-cruciate ligament (ACL) reconstruction for ACL rupture (n = 24); (b) IFP from elderly cadaver donors (n = 23). After histopathological score assignment to confirm the absence of inflammatory features (i.e., inflammatory infiltrate and increased vascularity), the adipocytes morphology was determined; moreover, extracellular matrix proteins were studied through histology and Second Harmonic Generation approach, to determine collagens content and orientation by Fast Fourier Transform and OrientationJ. The two groups were matched for body mass index. No inflammatory signs were observed, while higher area, perimeter, and equivalent diameter and volume were detected for the adipocytes in the elderly group. Collagen III displayed higher values in the young group and a lower total collagen deposition with aging was identified. However, collagen I/III ratio and the global architecture of the samples were not affected. A higher content in elastic fibers was observed around the adipocytes for the ACL-IFPs and in the septa cadaver donor-IFPs, respectively. Age affects the characteristics of the IFP tissue also in absence of a pathological condition. Variable mechanical stimulation, depending on age-related different mobility, could be speculated to exert a role in tissue remodeling.

Infrapatellar Fat Pad-Synovial Membrane Anatomo-Fuctional Unit: Microscopic Basis for Piezo1/2 Mechanosensors Involvement in Osteoarthritis Pain

“…In fact, several evidences based on macroscopic anatomy, imaging, histopathology (the IFP and SM) show increase of inflammatory features in OA ( Klein-Wieringa et al, 2016 ) and molecular biology, highlight the tight interaction among these structures, supporting the existence of a IFP-SM anatomo-functional unit (AFU) ( Macchi et al, 2018 ). Despite physiological age-related modifications ( Stocco et al, 2021 ) the AFU seems to be actively involved in OA pathogenesis and pain ( Macchi et al, 2018 ; Belluzzi et al, 2019a ).…”

Development and In Vitro/In Vivo Comparative Characterization of Cryopreserved and Decellularized Tracheal Grafts

“…Semi-quantitative analysis of ECM elements in native, cryopreserved, and decellularized tracheas was performed by previously standardized protocols [ 45 , 47 ]. Photomicrographs were acquired under a Leica DM4500B microscope (Leica Microsystems) connected to a Leica DFC320 high-resolution digital camera (Leica Microsystems).…”

“…The transform-based texture analysis techniques convert the image into a new form using the spatial frequency properties of the pixel intensity variations allowing the extraction of textural characteristics from the image. Highly oriented fibre in a single direction shows an elliptic shape; whether a circular shape represents fibre spread in all directions [ 44 , 45 , 47 , 50 , 52 , 53 ]. Five samples/group were considered in this analysis; for each sample, 5 different areas were analyzed.…”

Meniscus regeneration by 3D printing technologies: Current advances and future perspectives

“…[61][62][63] Additionally, age alone is a critical (and unavoidable) risk factor too. [64][65][66][67][68] Typical meniscal tears distinguish five patterns clearly recognizable trough Magnetic Resonance Imaging (MRI); these include radial, horizontal longitudinal, vertical longitudinal, oblique, and a complex combination of multiple patterns. The healthy meniscus typically experiences longitudinal tears, bucket-handle tears (vertical split and in line with the orientation of the circumferential collagen fibers), or radial tears (perpendicular split to the long axis).…”