胞外體

胞外體

科技的進步為人類提供了工具去探索體內細胞更微小部分。

過程中,我們發現了這些信號器在辨認疾病、生物入侵健康和治療疾病方面有強大作用。

胞外體就是其中一種具有深厚潛力影響衰老的信號。

什麼是胞外體 (Exosome)?

Exosomes are nano-sized extracellular vesicles. Unlike intracellular signals, that function within the cells, exosomes travel in the extracellular fluid (like the blood), communicating from one cell to another. They are often referred to as membrane-bound vesicles and although not a cell, they have a surrounding wall protecting the contents it carries. To deliver its message, it fuses its membrane with the target cell’s wall, therefore spilling its contents before being recycled.

Discovered in the 1980s, exosomes were first thought to be cellular garbage bags carrying waste around. In reality, exosomes carry a wide range of material that is used in communication including various proteins, molecules and genetic material. In fact, by inspecting the contents of exosomes scientists can analyze the signals they are sending and distinguish healthy cells from diseased cells.

胞外體及衰老

作為主力的信號傳遞者,胞外體在加速或抗衰老過程中擔當着重要角色。其中主要角色有: 

細胞衰老

隨著年齡增長,許多細胞會受損,不能再健康地複制細胞。由於未能及時分解及回收,受損的細胞會繼續主動傳遞對身體有害的信號。這些被稱為衰老的細胞會釋放更多的毒性胞外體,而這些胞外體將衰老的狀態當作信息般傳播到鄰近的細胞,並加速引致炎症和癌症等慢性疾病。相反地科學家已經從遺傳物質(miRNA)中識別出能有效抑制細胞衰老的胞外體信號。

2. 壓力及衰老

研究表示,壓力與胞外體傳遞信號的種類有直接的關係。這些信號就像危險警告一樣,允許其他細胞響應給予的壓力而事先進行先發製人的改變。 儘管有效用,但在長期壓力下,這些信號會促使炎症的環境,導致加速衰老和引致慢性疾病。

3. 有毒蛋白質

衰老的細胞可以通過胞外體,傳遞含毒性的蛋白質和mRNA的信號。這些信號不但能致病,更與神經退化障礙及因衰老的認知能力下降有關。

胞外體療法

胞外體沒有好壞之分,因為它們只是細胞之間的訊息傳遞者。而實質上,它們的存在是一個令人振奮的研究新領域,例如從衰老細胞中找出抑制負面信號傳遞的方法、 調節正面信號,在指定情況下利用生物駭客技術等。鑑於其廣泛的應用和對衰老的可改變的能力,胞外體療法絕對是抗衰老醫學的嶄新療法。

研究顯示,胞外體療法具有以下功能:

  • 傷口癒合
  • 骨骼再生
  • 促進循環
  • 新血管形成(血管生成)
  • 激活 Nrf2 的抗氧化和抗炎功能

參考文獻

  1. Panagiotou N, Neytchev O, Selman C, Shiels PG. Extracellular Vesicles, Ageing, and Therapeutic Interventions. Cells. 2018;7(8):110. Published 2018 Aug 18. doi:10.3390/cells7080110
  2. D’Anca M, Fenoglio C, Serpente M, Arosio B, Cesari M, Scarpini EA, Galimberti D. Exosome Determinants of Physiological Aging and Age-Related Neurodegenerative Diseases. Frontiers in Aging Neuroscience. 2019;11:232. 
  3. Bellingham, S. A., Guo, B. B., Coleman, B. M., and Hill, A. F. (2012). Exosomes: vehicles for the transfer of toxic proteins associated with neurodegenerative diseases? Front. Physiol. 3:124. doi: 10.3389/fphys.2012.00124
  4. Pusic, A. D., and Kraig, R. P. (2014). Youth and environmental enrichment generate serum exosomes containing miR-219 that promote CNS myelination. Glia 62, 284–299. doi: 10.1002/glia.22606
  5. Zhang J, Guan J, Niu X, Hu G, Guo S, Li Q, et al. Exosomes released from human induced pluripotent stem cells-derived MSCs facilitate cutaneous wound healing by promoting collagen synthesis and angiogenesis. J Transl Med. 2015;13:49.
  6. Zhang J, Liu X, Li H, Chen C, Hu B, Niu X, et al. Exosomes/tricalcium phosphate combination scaffolds can enhance bone regeneration by activating the PI3K/Akt signaling pathway. Stem Cell Res Ther. 2016;7(1):136.
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