Collagen Piezoelectric effect induce bone healing. 2007년

[문형철]

piezoelectric effect는 connective tissue 등 인체의 모든 조직에 중요한 재생자극을 설명하는 물리학적 용어

결론 collagen deformation으로 유도된 piezoelectric effect는 bone mineralization process의 방아쇠 인자로 작용. 

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Abstract

The collagen includes 90% of the organic matrix of the bones. Bone healing and growth are controlled by the rate of deposition of hydroxyapatite (HA). This process have been so far accredited to the work of osteoblasts, which are attracted by the electrical dipoles produced either by piezoelectricity, due to deformation of the bone, specially the collagen in it, or due to outside electrical stimuli. 

- collagen은 bone organic maxtrx의 90%를 포함. 

- bone healing and growth는 hydorxyapatite의 deposition비율에 의해 조절됨. 이 과정은 어느 정도까지는 osteoblast의 능력에 의존하고, 이는 piezoelectricity에 의한  electrical dipoles produced에 의해 영향을 받음. 

참고) The basic calcium phosphate mineral, hydroxyapatite (HAP) (Ca10(PO4)6(OH)2)), is the prototype of one of the major constituents of bone and teeth.

- 칼슘 인산 미네랄인 하이드록시아파타이트는 뼈와 이의 주요구성물질의 하나인 형태. 

The main purpose of this work was to study the influence of the effect of piezoelectricity of elastically deformed cortical bone collagen, on the mineralization process without bone cells. 

- 이 연구의 목적은bone mineralization과정에서 bone collagen에 영향을 주는 piezoelectricity에 대한 것

The collagen type I was obtained by rabbit’s bones decalcification using EDTA 0.5 M pH 7.4 treatment. The rectangular samples of bone collagen were bending to induce piezoelectricity (Figure B) and immersed into Simulated Body Fluid (SBF) using the biomimetic method for 5 weeks. 

- 토끼의 콜라겐 type1이 얻어짐. 

This effect induces a net negative charge on the compression side which induces a preferential deposition of mineral on the surface compared with the tension side (net positively charge), as previously described [Noris-Suarez K. et al., Biom. 8(3): 941-948]. Controls (undeformed) and deformed samples were analyzed by SEM to verify mineral deposition on both sides. The micrographs of SEM of the deformed collagen immersed for different periods of time 3, 4 and 5 weeks are shown. Figure A corresponds to deformed collagen under compression immersed for 31/2 weeks in SBF; it shows the crosslinks between each collagen fibbers and how the initial process of apatite nucleation on the different collagen bands occurs. Figure B corresponds to the deformed collagen immersed for 4 weeks in SBF and it is possible to observe that the mineral deposition is much higher on the compression deformed side than at the surface under tension deformation. This preferential deposition is attributed to the piezoelectric effect generated by the mechanical deformation on the collagen, which induces a dipole orientation on the material, as an effect of the internal reorganization of collagen fibbers. In Figures C.I and C.II we can detail the mineral growth on the deformed collagen under compression and immersed in SBF for 5 weeks. The apatite particles cover the fibbers and forms conglomerates, compared with the deformed collagen site under tension, in same conditions (micrograph C.III), only have a few particles of mineral disperse on the surface. 

Probably the mineral deposited in the zone of the collagen of the cortical bone under compression is an amorphous phase of apatite precursor of crystals of hydroxyapatite. 

Our results demonstrate that this piezoelectric effect induced by collagen deformation could act as initiators of the mineralization process. The results of this study showed that the piezoelectric phenomena of bone collagen promotes mineralization on the compression side more than on the tension side compared with undeformed surface in absence of bone cells.

- collagen deformation으로 유도된 piezoelectric effect는 bone mineralization process의 방아쇠 인자로 작용. 

- 이 작용은 compression 방향이 좀더 효과적.

Figure 1: SEM micrographs of deformed bone collagen. A) Compression side immersed in SBF for 31/2 weeks. B)

Samples immersed in SBF for 4 weeks C) Samples immersed in SBF for 5 weeks: I) Compression side: Mineral

growth on collagen surface, II) Compression side: Mineral deposition detailed on collagen fibers, III) Tension

side: collagen fibbers.

[박건용]

1. 결합조직은 자극을 주면 전기자극으로 바뀌고 조직이 재배열된다. 이를 piezoelectricity라 한다. 중요한 것은 방향이다. 자극을 받으면 fibroblast, osteoblast의 도움으로 새로 배열된다. 부상 후 초기 자극이 중요하다. 부상 후 적절한 자극이 없으면 움직임에 적합한 일정한 방향으로 재배열 되지 못한다. 특히 compensation movement를 지속하면 더 나빠진다. 2. collagen deformation으로 유도된 piezoelectric effect는 bone mineralization process의 방아쇠 인자로 작용. tension side 보다 compression side에 좀 더 효과적. 3.piezoelectricity 자극 중 가장 강력한 자극은 "인체 스스로 움직이는 자극"이 최고의 자극.