E. Gacasan (La Jolla, US)

University of California San Diego Bioengineering

Presenter Of 1 Presentation

Poster Animal Models

P003 - Volumetric Growth of Distal Femoral Cartilage and Bone during Murine Postnatal Development follows Gompertz Law

Presentation Topic
Animal Models
Date
13.04.2022
Lecture Time
09:30 - 09:30
Room
Exhibition Foyer
Session Name
7.3 - Poster Viewing / Coffee Break / Exhibition
Session Type
Poster Session
Disclosure
R. Sah: Cartilage: Editorial or governing board, Osteoarthritis and Cartilage: Editorial or governing board, GlaxoSmithKline: stockholder, Johnson & Johnson: stockholder, Medtronic: stockholder
ICRS Award
Certificate of Merit

Abstract

Purpose

In skeletally immature individuals, the covering of bone ends includes a layer of epiphyseal and articular cartilage known as the articular–epiphyseal cartilage complex (AECC). Although initially a contiguous cartilaginous element, the AECC encompasses tissue that becomes the articular cartilage, growth plate, and a secondary ossification center (SOC). During postnatal development joint size increases and cartilage thickness decreases, however the mechanisms that dictate cartilage maturation and joint shaping remain undetermined. This study aims to (1) illustrate and qualitatively compare shape changes of the bone-cartilage interface and (2) quantitatively assess and model volumetric growth of the distal femoral SOC during normal murine postnatal development.

Methods and Materials

With IACUC approval, male wild-type CD1 mice (P0, P7, P14, P21, P28, P35, and P42; n=2-3/age) were sacrificed, perfusion fixed, skinned and eviscerated, then dehydrated to 70% ethanol before imaging by micro-computed tomography at (9 μm)3 voxel resolution. Volume of the left distal femur SOC was calculated by semi-automatic segmentation. SOC volume (V(t)) was fit to a Gompertz sigmoid model (V(t)=V(t=P42)*exp(-exp(-k(t-T))) with 3 parameters (V(t=P42): asymptote/mature value, T: time at inflection, k: growth rate coefficient).

Results

Although the SOC was not evident at P0, it increased in size between P7 (0.3±0.1 mm3 ) and P42 (~1900%; 6.4±0.1 mm3 ). The SOC initially formed as a small ellipsoidal structure followed by protrusion of the condyles, and formation of the trochlear ridge and intercondylar notch. Increase in SOC volume followed Gompertz function (R2=0.98, RMSE = 0.4), such that growth was slowest at the start and end of the time assessed, with an inflection point at T=~11 days postnatal and growth rate coefficient of k=0.23 1/days.

20211023_icrs_fig.png

Conclusion

Growth of the murine distal femoral SOC during postnatal development follows a sigmoid model indicating 3 phases of growth: the initial lag, the log, and the diminishing growth phases, where mechanisms of growth and maturation may vary

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Presenter Of 1 Presentation

Animal Models

P003 - Volumetric Growth of Distal Femoral Cartilage and Bone during Murine Postnatal Development follows Gompertz Law

Abstract

Purpose

In skeletally immature individuals, the covering of bone ends includes a layer of epiphyseal and articular cartilage known as the articular–epiphyseal cartilage complex (AECC). Although initially a contiguous cartilaginous element, the AECC encompasses tissue that becomes the articular cartilage, growth plate, and a secondary ossification center (SOC). During postnatal development joint size increases and cartilage thickness decreases, however the mechanisms that dictate cartilage maturation and joint shaping remain undetermined. This study aims to (1) illustrate and qualitatively compare shape changes of the bone-cartilage interface and (2) quantitatively assess and model volumetric growth of the distal femoral SOC during normal murine postnatal development.

Methods and Materials

With IACUC approval, male wild-type CD1 mice (P0, P7, P14, P21, P28, P35, and P42; n=2-3/age) were sacrificed, perfusion fixed, skinned and eviscerated, then dehydrated to 70% ethanol before imaging by micro-computed tomography at (9 μm)3 voxel resolution. Volume of the left distal femur SOC was calculated by semi-automatic segmentation. SOC volume (V(t)) was fit to a Gompertz sigmoid model (V(t)=V(t=P42)*exp(-exp(-k(t-T))) with 3 parameters (V(t=P42): asymptote/mature value, T: time at inflection, k: growth rate coefficient).

Results

Although the SOC was not evident at P0, it increased in size between P7 (0.3±0.1 mm3 ) and P42 (~1900%; 6.4±0.1 mm3 ). The SOC initially formed as a small ellipsoidal structure followed by protrusion of the condyles, and formation of the trochlear ridge and intercondylar notch. Increase in SOC volume followed Gompertz function (R2=0.98, RMSE = 0.4), such that growth was slowest at the start and end of the time assessed, with an inflection point at T=~11 days postnatal and growth rate coefficient of k=0.23 1/days.

20211023_icrs_fig.png

Conclusion

Growth of the murine distal femoral SOC during postnatal development follows a sigmoid model indicating 3 phases of growth: the initial lag, the log, and the diminishing growth phases, where mechanisms of growth and maturation may vary

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