Changes in Matrix Components in the Developing Human Meniscus

Abstract

Background: Treatment of meniscal tears is necessary to maintain the long-term health of the knee joint. Morphological elements, particularly vascularity, that play an important role in meniscal healing are known to change during skeletal development. Purpose: To quantitatively evaluate meniscal vascularity, cellularity, collagen, and proteoglycan content by age and location during skeletal development. Study Design: Descriptive laboratory study. Methods: Medial and lateral menisci from 14 male and 7 female cadavers aged 1 month to 11 years were collected and evaluated. For each meniscus, histologic and immunohistologic techniques were used to establish the ratio of the area of proteoglycan (safranin O) positivity to the total area (proteoglycan ratio), collagen type I and type II immunostaining positivity, number of blood vessels, and cell density. These features were evaluated over the entire meniscus and also separately in 5 circumferential segments: anterior root, anterior horn, body, posterior horn, and posterior root. Additionally, cell density and number of blood vessels were examined in 3 radial regions: inner, middle, and periphery. Results: Age was associated with a decrease in meniscal vessel count and cell density, while the proteoglycan ratio increased with skeletal maturity. Differences in vessel counts, cellular density, and proteoglycan ratio in different anatomic segments as well as in the inner, middle, and peripheral regions of the developing menisci were also observed. Collagen immunostaining results were inconsistent and not analyzed. Conclusion: The cellularity and vascularity of the developing meniscus decrease with age and the proteoglycan content increases with age. All of these parameters are influenced by location within the meniscus. Clinical Relevance: Age and location differences in meniscal morphology, particularly in the number of blood vessels, are expected to influence meniscal healing.

Yucatan Minipig Knee Meniscus Regional Biomechanics and Biochemical Structure Support its Suitability as a Large Animal Model for Translational Research

“…The posterior regions of both minipig menisci were significantly wider than their respective anterior and central regions, similar to human menisci; the posterior region of the lateral minipig meniscus, the widest by average in this study, was only 2% smaller than the average width reported for the lateral meniscus in the human. Additionally, comparable to what is seen in humans ( Chevrier et al, 2009 ; Fedje-Johnston et al, 2021 ), histology of minipig meniscus cross sections showed a collagen network throughout the tissue, a positive staining for GAG, and cells dispersed throughout the tissue ( Figure 3 ). Overall, minipig knee menisci provide gross morphological similarities to humans in terms of their peripheral height and regional width, which could allow for the ready implantation and, eventually, translation of engineered tissues for their repair or replacement.…”

Age-Related Changes in the Microvascular Density of the Human Meniscus

“…Because of the rarity of the specimens, we decided to pool the data. Fedje-Johnston et al 13 recently reported a higher cell density for the medial compared with the lateral meniscus in a cohort aged 1 month to 11 years. Crawford et al 7 could not detect a difference in vessel penetration between the medial and lateral meniscus.…”

“…The American Journal of Sports Medicine 2021;49 (13):3544-3550 DOI: 10.1177/03635465211039865 Ó 2021 The Author(s) outcome measures at a minimum 2-year follow-up, regardless of the meniscal tear zone. The authors recommend repair for meniscal tears in all 3 vascular zones, although improved outcomes can be achieved when the repairs are performed in the RR and RW zones.…”

The role of patient characteristics and the effects of angiogenic therapies on the microvasculature of the meniscus: A systematic review

“…The search identified 411 articles, of which 352 were excluded based on title and abstract screening, and another twentyfive after full-text reading (Figure 2) [24]. Thirteen studies were included, which reported on patient characteristics affecting the microvasculature of the human meniscus (Table 1) [11][12][13][27][28][29][30][31][32][33][34][35][36], and another eleven studies reported on therapies enhancing the microvascularization of meniscal tissue (Table 2) [37][38][39][40][41][42][43][44][45][46][47]. Quality of the included studies, as assessed by the AQUA tool, is provided in Table 3.…”

“…Ten studies (3 HQ, 3 IQ, and 4 LQ) reported the effect of age on the microvascularization of the human meniscus (Table 1) [11][12][13][27][28][29][30][31][32]35]. Cadaveric studies have shown that the entire meniscus is vascularized around birth, but with increasing age, the vascularity gradually decreases from the inner to the peripheral margin [11,28].…”