材料及力學因素對磷酸鈣陶瓷骨誘導性的影響
發(fā)布時間：2018-08-28 09:53
【摘要】：目前研究認為在磷酸鈣生物陶瓷骨誘導性潛能中發(fā)揮作用的材料特性包括:化學成分、宏觀及微觀幾何結構和孔隙率。此外,生物體的種屬及植入部位也會影響材料的骨誘導活性。盡管對磷酸鈣生物陶瓷骨誘導現(xiàn)象的生物機制進行了大量的研究,卻仍缺乏對這些機制的系統(tǒng)性理解,這限制了生物陶瓷在臨床骨再生治療中的廣泛應用。本研究綜合考慮磷酸鈣生物陶瓷的宏觀孔隙結構和微結構表面特性在異位骨形成中的作用,以及生理環(huán)境下應力刺激對骨發(fā)生、發(fā)育及動態(tài)平衡起到的重要作用,從體內應力環(huán)境、支架孔隙結構和支架內細胞受到的力學刺激之間的相關性角度入手,基于生物力學調控理論,對生物材料通過自身結構特征調控骨誘導發(fā)生的機制進行探討。為深入研究磷酸鈣生物陶瓷與骨誘導發(fā)生的相關性機制提供新途徑,并對優(yōu)化設計可控骨誘導性的磷酸鈣生物陶瓷提供實驗和理論依據(jù)。包括以下內容:(1)將具有不同宏觀孔隙形狀和尺寸的羥基磷灰石顆粒堆積支架(HA spheres accumulating scaffolds, HASAs)和羥基磷灰石顆粒造孔支架(HAporogen-pore scaffolds,HAPPs)植入狗的背肌和腹腔,系統(tǒng)比較宏孔形狀和尺寸對支架異位成骨能力的影響。并構建三維支架理論模型,對支架內微流體動力環(huán)境進行流動仿真模擬,探討材料的宏觀結構因素通過微流體動力途徑轉換為骨誘導調控信號的相關性。研究表明宏孔尺寸和形狀對HA多孔支架骨誘導性有顯著的影響,并且這種影響是兩種結構變量共同作用的結果。流體仿真計算結果表明微流體動力環(huán)境影響支架內新骨形成和分布。研究發(fā)現(xiàn)微流體動力環(huán)境是材料的宏孔結構因素轉換為骨誘導生物調控信號的重要途徑。(2)通過調節(jié)溶膠-凝膠體系中HA/Chitin的質量比制備具有不同表面微形貌(粗糙度、比表面積和微孔隙率)的HA球形顆粒。體外細胞實驗結果證實材料表面微形貌對BM-MSCs的生物行為有明顯影響,多孔粗糙表面在與BM-MSCs復合初期更有利于細胞的增殖,后期則利于細胞骨向分化。細胞在與致密光滑表面復合初期因增殖很快受限,因此提前促進了 BM-MSCs的骨向分化�？傮w來說多孔粗糙表面對BM-MSCs具有更好的促增殖和分化作用。每種表面都具有良好的細胞相容性。體內動物實驗結果表明,本研究所用的具有不同表面微形貌的HA多孔顆粒支架均具有良好的生物相容性,而粗糙表面更利于支架植入體內非骨部位后的異位骨形成。(3)在體外構建生理-微振動應力環(huán)境,研究微振動應力刺激(振幅≤50μm、強度1×g、頻率范圍在1-100Hz的極低幅度、低強度、低頻率的力學環(huán)境,MV)對羥基磷灰石多孔支架材料上復合的BM-MSCs成骨分化和細胞外基質礦化的影響,探討微振動對羥基磷灰石生物活性及生物力學性能的影響,以及與羥基磷灰石陶瓷骨誘導性之間的關聯(lián)性。研究發(fā)現(xiàn)微振動應力環(huán)境能提升HA多孔支架生物礦化能力,有利于構建成骨環(huán)境;微振動應力環(huán)境通過三維多孔支架發(fā)生力學信號轉換誘導BM-MSCs成骨分化;并且微振動應力環(huán)境和HA多孔支架協(xié)同提高了 BM-MSCs成骨相關基因Cbfal/Runx2、Col-I、ALP、OC的表達和成骨特征性蛋白ALP的表達。(4)將HA顆粒堆積支架(HASAs)植入實驗動物腹腔內構建體內組織工程骨移植物,修復自體股骨節(jié)段性骨缺損,以探討利用多孔貫通生物材料支架在體內自然生理環(huán)境異位培養(yǎng)組織工程化骨移植物修復大節(jié)段承重骨缺損的可能性。同時,也探討腹腔作為自體生物反應器構建特定形狀、大體積的組織工程骨移植物的可能性。研究證明腹腔內低血供、低應力負荷和缺少干細胞源性物質的生理環(huán)境具有作為體內生物反應器構建組織工程化骨移植物的可能。并成功將腹腔中構建的具有自體骨組織的骨移植物應用于節(jié)段性承重骨缺損修復。
[Abstract]:Current studies have shown that the material properties that play a role in the bone induction potential of calcium phosphate bioceramics include chemical composition, macroscopic and microscopic geometric structures and porosity. However, there is still a lack of systematic understanding of these mechanisms, which limits the wide application of Bioceramics in clinical bone regeneration therapy. Dynamic balance plays an important role in bone induction. Based on the theory of biomechanical regulation, the mechanism of biomaterials regulating bone induction through their own structural characteristics is discussed from the point of view of the correlation between stress environment in vivo, pore structure of scaffolds and mechanical stimulation of cells in scaffolds. This study provides a new way to optimize the design of bone-inducible calcium phosphate bioceramics, including: (1) HA spheres accumulating scaffolds (HASAs) and hydroxyapatite particles with different macroporous shapes and sizes. Haporogen-pore scaffolds (HAPPs) were implanted into the dorsal and abdominal muscles of dogs to compare the effects of macropore shape and size on the ectopic osteogenesis of the scaffolds. A three-dimensional scaffold model was constructed to simulate the microhydrodynamic environment in the scaffolds and explore the macrostructural factors of the scaffolds through the microhydrodynamic pathway. Studies have shown that macropore size and shape have a significant effect on the osteoinductivity of HA porous scaffolds, and this effect is the result of the interaction of two structural variables. Force environment is an important way to convert macroporous structural factors into bone-induced biological signals. (2) HA spherical particles with different surface micromorphologies (roughness, specific surface area and microporosity) were prepared by adjusting the mass ratio of HA/Chitin in sol-gel system. Biological behavior of BM-MSCs was significantly influenced by porous rough surfaces, which were more conducive to cell proliferation at the early stage of BM-MSCs compounding, but more conducive to cell bone differentiation at the later stage. The results of in vivo animal experiments showed that HA porous particle scaffolds with different surface micromorphologies had good biocompatibility, and rough surfaces were more conducive to heterotopic bone formation after implantation in non-bone sites in vivo. To study the effect of micro-vibration stress stimulation (amplitude < 50 micron, intensity 1 xg, frequency range 1-100Hz, mechanical environment of low amplitude, low strength, low frequency, MV) on the osteogenic differentiation and extracellular matrix mineralization of BM-MSCs on porous scaffolds, and to explore the effect of micro-vibration on the formation of hydroxyapatite. It was found that the micro-vibration stress environment could enhance the biomineralization ability of HA porous scaffolds and facilitate the construction of osteogenic environment, and the micro-vibration stress environment could induce BM-MSCs osteogenic differentiation through mechanical signal transformation of three-dimensional porous scaffolds. The expression of BM-MSCs osteogenesis-related genes Cbfal/Runx2, Col-I, ALP, OC and the expression of osteogenic characteristic protein ALP were enhanced by microvibration stress and HA porous scaffolds. (4) HA granular accumulation scaffold (HASAs) was implanted into the abdominal cavity of experimental animals to construct in vivo tissue-engineered bone grafts to repair segmental bone defects of the femur. The possibility of repairing large segmental load-bearing bone defects with tissue-engineered bone grafts in heterotopic culture in vivo using porous perforated biomaterial scaffolds was also discussed. The possibility of constructing large-scale tissue-engineered bone grafts in the abdominal cavity as an autologous bioreactor was also discussed. It is possible to construct tissue-engineered bone grafts in vivo as bioreactor under mechanical loading and lack of stem cell-derived materials. Bone grafts with autogenous bone tissue from abdominal cavity were successfully used to repair segmental load-bearing bone defects.
【學位授予單位】：西南交通大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：R318.08
本文編號：2209038
[Abstract]:Current studies have shown that the material properties that play a role in the bone induction potential of calcium phosphate bioceramics include chemical composition, macroscopic and microscopic geometric structures and porosity. However, there is still a lack of systematic understanding of these mechanisms, which limits the wide application of Bioceramics in clinical bone regeneration therapy. Dynamic balance plays an important role in bone induction. Based on the theory of biomechanical regulation, the mechanism of biomaterials regulating bone induction through their own structural characteristics is discussed from the point of view of the correlation between stress environment in vivo, pore structure of scaffolds and mechanical stimulation of cells in scaffolds. This study provides a new way to optimize the design of bone-inducible calcium phosphate bioceramics, including: (1) HA spheres accumulating scaffolds (HASAs) and hydroxyapatite particles with different macroporous shapes and sizes. Haporogen-pore scaffolds (HAPPs) were implanted into the dorsal and abdominal muscles of dogs to compare the effects of macropore shape and size on the ectopic osteogenesis of the scaffolds. A three-dimensional scaffold model was constructed to simulate the microhydrodynamic environment in the scaffolds and explore the macrostructural factors of the scaffolds through the microhydrodynamic pathway. Studies have shown that macropore size and shape have a significant effect on the osteoinductivity of HA porous scaffolds, and this effect is the result of the interaction of two structural variables. Force environment is an important way to convert macroporous structural factors into bone-induced biological signals. (2) HA spherical particles with different surface micromorphologies (roughness, specific surface area and microporosity) were prepared by adjusting the mass ratio of HA/Chitin in sol-gel system. Biological behavior of BM-MSCs was significantly influenced by porous rough surfaces, which were more conducive to cell proliferation at the early stage of BM-MSCs compounding, but more conducive to cell bone differentiation at the later stage. The results of in vivo animal experiments showed that HA porous particle scaffolds with different surface micromorphologies had good biocompatibility, and rough surfaces were more conducive to heterotopic bone formation after implantation in non-bone sites in vivo. To study the effect of micro-vibration stress stimulation (amplitude < 50 micron, intensity 1 xg, frequency range 1-100Hz, mechanical environment of low amplitude, low strength, low frequency, MV) on the osteogenic differentiation and extracellular matrix mineralization of BM-MSCs on porous scaffolds, and to explore the effect of micro-vibration on the formation of hydroxyapatite. It was found that the micro-vibration stress environment could enhance the biomineralization ability of HA porous scaffolds and facilitate the construction of osteogenic environment, and the micro-vibration stress environment could induce BM-MSCs osteogenic differentiation through mechanical signal transformation of three-dimensional porous scaffolds. The expression of BM-MSCs osteogenesis-related genes Cbfal/Runx2, Col-I, ALP, OC and the expression of osteogenic characteristic protein ALP were enhanced by microvibration stress and HA porous scaffolds. (4) HA granular accumulation scaffold (HASAs) was implanted into the abdominal cavity of experimental animals to construct in vivo tissue-engineered bone grafts to repair segmental bone defects of the femur. The possibility of repairing large segmental load-bearing bone defects with tissue-engineered bone grafts in heterotopic culture in vivo using porous perforated biomaterial scaffolds was also discussed. The possibility of constructing large-scale tissue-engineered bone grafts in the abdominal cavity as an autologous bioreactor was also discussed. It is possible to construct tissue-engineered bone grafts in vivo as bioreactor under mechanical loading and lack of stem cell-derived materials. Bone grafts with autogenous bone tissue from abdominal cavity were successfully used to repair segmental load-bearing bone defects.
【學位授予單位】：西南交通大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：R318.08
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