骺軟骨板是位於長骨骨骺的一個軟骨結構，其主要功用為使骨骼延伸生長。 若人類骺軟骨板基因出現障礙，骨骼生長往往會受到嚴重的影響，使骨骼變得短小、畸形，造成殘障。此外，一些後天的系統性失調也會損害骺軟骨板的正常運作，導致矮小症。現今常用來醫治骨骼生長障礙的包括重組的人類生長荷爾蒙。然而，它的功效並非顯著，亦帶來很多的副作用；因此，我們希望能尋求更好的醫治方法。 / 近有的研究結果顯示，很多的內分泌及分泌因子能夠刺激骺軟骨板進行軟骨增生。但是，研究者卻往往未能將這些因子轉化及運用作醫療用途，原因是它們通常都是局部性地於骺軟骨板產出及發生效用。倘若以上提及的生長因子能給骺軟骨板的靶子蛋白鏈準確地被帶往骺軟骨板，那麼這些因子便能有效地被利用作治療用途，而其效能亦會給大大提高，副作用也會被減低。因此，我們現在進行研究的首要目標為於採用噬菌體展示和酵母展示方法， 尋找那些能認辨出骺軟骨板的靶子蛋白鏈及單鏈抗體。 / 於噬菌體展示庫裡，我們找出了兩條能認辨出小鼠骨骼軟骨細胞的靶子蛋白鏈 － C1 (RLDPTSYLRTFW) 和 C19 (HDSQLEALIKFM)。然而於體外測試實驗中， 它們對軟骨細胞及細胞外基質只擁有中度的親近性和特異性。此後，於酵母展示庫裡，我們亦發現三條可認辨某骺軟骨板蛋白的單鏈抗體 － 它們的親近性甚高 (達至1 nM)，而其對軟骨組織的特異性也為良好 (它們只認辨軟骨組織，但卻沒能認辨出其他的軟組織，包括腦、心臟、肝臟、肺臟、腎臟、脾臟、小腸及肌肉)。 其後，於小鼠胚胎免疫染色測試實驗中，這些單鏈抗體只亦選擇地認辨軟骨組織。再者，當這些單鏈抗體被注射入小鼠的靜脈中，它們也會準確地停留在軟骨組織裡，顯示出其特異性於體內測試實驗中亦存在。 / 總括而言，利用噬菌體展示和酵母展示方法，我們發現了一些能認辨出骺軟骨板的靶子蛋白鏈及單鏈抗體。這些單鏈抗體擁有對軟骨組織非常高的親近性和特異性。我們預計，若然將這些單鏈抗體和內分泌及分泌因子連結在一起，它們或能成為醫治骨骼生長障礙的新方法。 / The growth plate is a specialized cartilage structure at the ends of long bones that is responsible for bone elongation. Many human genetic disorders of the growth plate impair skeletal growth, often resulting in bones that are severely short and malformed, causing serious disability. Many acquired systemic disorders also impair growth plate function, causing short stature. Currently, recombinant human growth hormone is used to treat growth disorders, but it has limited efficacy for severe diseases and causes significant adverse effects. / Recent studies have identified many endocrine and paracrine factors that are capable of promoting chondrogenesis at the growth plate. However, the development of these molecules into effective therapies has been hampered by their action mechanism; they are produced locally and act locally in the growth plate and thus fail to lend themselves to systemic therapeutic approaches. We envisioned that, if these growth factors could be linked to growth plate-targeting peptides or polypeptides and then administered systemically, these molecules might provide a better treatment strategy for growth disorders because targeting might augment the therapeutic effect on the growth plate but diminish undesirable effects on non-target tissues. Toward this goal, we sought to identify peptides and antibody fragments that bind to cartilage tissue using phage display and yeast display technologies. / We used a phage display library that expressed linear peptides of 12 random amino acids on the phage surface and then selected for binding to murine primary cultured chondrocytes. This approach successfully identified two peptides, namely C1 (RLDPTSYLRTFW) and C19 (HDSQLEALIKFM), which exhibited moderate binding affinity and specificity to chondrocytes and extracellular matrix in vitro. We also used a yeast display library to identify three single-chain variable(scFv) antibody fragments that bound strongly to a growth plate-specific protein(EC50 values less than 1 nM). These antibody fragments demonstrated specific binding in vitro to homogenates of cartilage tissues, but not homogenates of brain, heart, liver, lung, kidney, spleen, small intestine, or muscle. Moreover, they also exhibited tissue-specific binding to cartilage structures in sections of mouse embryos. When these purified antibody fragments were injected intravenously in mice, they localized to cartilage and were not detectable in other tissues, including brain, heart, liver, lung, kidney, spleen, small intestine, or muscle, indicating that the antibody fragments were capable of specifically targeting cartilage tissue in vivo. / In conclusion, we employed phage display and yeast display methods to identify peptides and antibody fragments that bind to cartilage tissues. The selected antibody fragments showed particularly high binding affinity and specificity to cartilage. Conjugating these antibody fragments to endocrine and paracrine signaling molecules has the potential to provide targeted therapy for growth plate disorders. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Cheung, Sao Fong. / Thesis (Ph.D.) Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 89-102). / Abstracts also in Chinese.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_1077670 |
| Date | January 2013 |
| Contributors | Cheung, Sao Fong (author.), Fung, Kwok-pui (thesis advisor.), Chinese University of Hong Kong Graduate School. Division of Biomedical Sciences, (degree granting institution.) |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography, text |
| Format | electronic resource, electronic resource, remote, 1 online resource (xvi, 102, 7 unnumbered leaves leaves) : illustrations (some color), computer, online resource |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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