多功能奈米載體應用於神經修復之幹細胞影像追蹤及磁操控研究

Abstract

幹細胞治療是現今再生醫學中最佳的治療方式。然而在體外增生幹細胞和在體內運輸幹細胞到病灶位置一直是一大挑戰，由於在體內中，幹細胞容易被身體循環代謝到肝和腎的位置，使得到達病灶位置的幹細胞是少之又少，進而使得幹細胞療效受到很大的限制，因此如何控制及導引幹細胞於病灶位置，以促進幹細胞療效，並且監測顯影幹細胞，是現今需要突破且克服的重要技術與研究主軸。本研究計劃主要是利用奈米金棒填充於包覆奈米氧化鐵之孔洞二氧化矽的特殊結構，來進行多功能奈米顯影劑載體於幹細胞導引治療的研發，包括 (i) 奈米金棒與奈米氧化鐵粒子及形態成長控制及合成研發，(ii)奈米氧化鐵及奈米金棒填充於孔洞二氧化矽結構的合成控制及特性探討，以發展使其形成具有磁特性與光特性的奈米顯影劑載體。(iii)奈米載體包覆生長因子的製程探討與生長因子釋放特性及對幹細胞行為的影響，(iv) 顯影劑載體與幹細胞之間相互作用探討(v)利用氧化鐵奈米粒子與光聲顯影特性，來追蹤該奈米顯影劑載體及幹細胞，(vi)利用磁導引的功能來研究導引幹細胞的分佈及顯影效果，(vii)透過雷射光源來操控生長因子的釋放於幹細胞中的變化與分化結果，以分析其彼此間的相互關係，進而可用來評估生長因子即時釋放量及模式對於幹細胞生長分化的影響。(viii)透過磁導引奈米顯影劑載體，來進行幹細胞於中風模型下之療效修復評估，以探討奈米顯影劑載體導引幹細胞於中風處的累積濃度與治療效率。 預定在這三年的研究計畫，將利用材料與生長因子的結合，針對此具有磁導引特性之多功能奈米顯影劑載體元件的合成製程，奈米粒子的物理及磁性與奈米金棒的光學特性及細胞毒性，生長因子釋放及操控與幹細胞導引等，進行相關重要的研究，設計與製備一種具磁導引多功能性的奈米顯影劑載體，此奈米載體具有生長因子操控釋放、光聲顯影與導引幹細胞之複合奈米顯影劑載體，搭配外加磁力的控制，期望在未來可以同步導引與追蹤幹細胞及即時偵測生長因子釋放的情形，以評估是否可達最佳治療效果的新世代幹細胞治療的需求。

Stem cell-based therapy has been one of the best documented approaches in regenerative medicine, promising cures for a multitude of diseases and disorders. However, the ex vivo expansion and in vivo delivery of stem cells are restricted by the limited availability of stem cell sources, the excessive cost of commercialization, and the anticipated difficulties of clinical translation and regulatory approval. An alternative to adoptively transferred stem cells are cell populations already present in a patient’s body, including stem/progenitor cells, which can be actively attracted to sites of injury. This technique, known as endogenous cell homing, has the potential to provide new therapeutic options for in situ tissue regeneration. In this study, a new type of magnetical delivery system based on gold nanorod-filled mesoporous silica nanobeads with exceptionally efficient and stable photoacoustic imaging modality will be synthesized. The novel nano-seaurchin structure is characteristic of high-density and well-dispersive gold nanorods (AuRNBs) in one mesoporous silica nanobead. The optical properties and photothermal stability of porous silica nanobeads with pore-filled gold nanorods (AuRNBs) under intense irradiation with nanosecond laser pulses were investigated by UV-Vis spectroscopy and transmission electron microsocopy. (i)synthesis of various aspect-ratio gold nanorods (AuRNBs) and superparamegnetic ieon oxide nanoparticles (SPIO) (ii) processing development and character analysis of AuRNBs-filled in SPIO-containing mesoporous silica nanobeads (iii)magnetic and photoacoustic imaging of the nanobeads (iv) The optical properties and photothermal stability of porous silica nanobeads with pore-filled gold nanorods (AuRNBs) under intense irradiation with nanosecond laser pulses were investigated by UV-Vis spectroscopy and transmission electron microsocopy.(v) neural growth factor release behavior and loading of the nanobeads and its effect on stem cell behavior (vi) Interaction of nanobeads with stem cells (vi) In-vivo imaging and distribution of stem cells under magnetically targeting nanobeads，(viii) Laser-induced growth factor release to stem cell and its effect on stem cell proliferation and differentiation. (ix) evaluation of stem cell based therapy in the tissue repairing ischemic brain following stroke through magnetic guilding。Through this project, we expect to develop the multifunctional magnetical AuRNBs which provided a stable photoacoustic signal and neutral stem cells tracking both in vitro and in vivo. In addition, the magnetical AuRNBs demonstrated relatively high cell viability and uptake efficiency along with stem cells homing for in situ tissue regeneration.