Introduction

• In the past decade, our understanding of how cells communicate has grown rapidly. Previously, communication between cells was limited to simple exchanges like hormones or local signals.
• It was discovered that cells use a system of extracellular vesicles, including exosomes, that can carry a variety of small and large molecules such as RNAs, DNA, and even entire organelles to regulate cell function.
• Electrical communication between cells was once thought to be limited to neurotransmitters in the nervous system. However, it’s now clear that most cells, both in mammals and other organisms, communicate through bioelectric systems that control many vital processes like growth, differentiation, and tissue repair.
• A new type of cell, called telocytes, was discovered. These long, thin cells use electrical, chemical, and epigenetic mechanisms, including the exchange of exosomes, to communicate and coordinate activities between different types of cells in tissues and organs.

What Are Telocytes?

• Telocytes are specialized cells that act as communication hubs between other cells. They are very long and thin, with arms that stretch out and make contact with other cells.
• Each telocyte contains a small nucleus and long, delicate arms called podomeres. These arms contain spots called podoms, which house the machinery needed for protein synthesis.
• The long arms of telocytes help them communicate with other cells through electrical signals, chemical exchanges, and the transfer of exosomes (tiny packages of molecules) between cells.

How Telocytes Communicate with Other Cells

• Telocytes are involved in exchanging signals with nearby cells, such as smooth muscle cells, immune cells, and stem cells. These signals help regulate cell behaviors like growth, repair, and immune responses.
• When a target cell is injured (e.g., a blood vessel), it sends out a chemical signal, such as hemoglobin. Telocytes take up this signal and “reprogram” themselves to respond appropriately by synthesizing proteins that help repair the injury.
• Telocytes can also interact with cells in the immune system. For example, if the target cell is an immune cell (like a macrophage), the telocyte’s machinery, set by exosome transfer, helps modulate immune responses.

Exosomes and Telocytes

• Exosomes are small vesicles that carry important information between cells. Telocytes play a key role in receiving and sending exosomes, which carry a wide range of molecules, including proteins, lipids, RNA, and other important cell signals.
• By taking up exosomes from nearby cells, telocytes reprogram themselves to handle specific tasks, such as tissue repair or immune modulation, without needing to send out long-distance signals.
• This process of exchanging exosomes between cells is similar to how communication happens at synapses in the nervous system, where signals are transferred between neurons.

Telocytes and Volume Transmission

• Volume transmission (VT) is a form of communication where signaling molecules (such as neurotransmitters or hormones) diffuse through the extracellular fluid (ECF) to affect target cells.
• Telocytes are involved in volume transmission because they can release and receive extracellular vesicles, including exosomes, that help transmit signals over long distances within tissues.
• The extracellular matrix (ECM), which is a network of proteins and other molecules, helps form pathways for these signals to travel between cells. Telocytes play a role in shaping these pathways, allowing signals to be transmitted effectively.

Telocytes in the Brain and Beyond

• Telocytes are found in many tissues, including the brain, where they interact with neural stem cells, blood vessels, and nerve fibers.
• In the brain, telocytes may help create extracellular pathways for volume transmission, allowing signals to travel more effectively across regions like the choroid plexus and meninges (protective layers surrounding the brain).
• These cells may also help guide the movement of stem cells to repair damage in the brain and other organs. For instance, telocytes in the subventricular zone might help stem cells migrate to the olfactory bulb, a region involved in smell.

Telocytes and Neurodegenerative Diseases

• Neurodegenerative diseases, such as Alzheimer’s and Parkinson’s, involve a variety of processes, including the accumulation of abnormal proteins, mitochondrial dysfunction, and loss of synaptic connections.
• Telocytes may play a role in these diseases by helping to regulate neural stem cells and maintaining the brain’s overall health.
• Research has shown that telocytes in areas like the choroid plexus may help clear abnormal proteins, such as amyloid plaques, from the brain, which is an important function in conditions like Alzheimer’s.
• In the future, telocytes may become a key target for therapies aimed at repairing or regenerating brain tissue, as they play a critical role in coordinating cellular communication and repair processes.

Conclusion

• Telocytes are a type of cell that plays a crucial role in cellular communication and tissue repair. They use a combination of electrical, chemical, and epigenetic signals, including the exchange of exosomes, to coordinate the activities of other cells.
• These cells are involved in volume transmission and help create pathways for signals to travel across tissues. They also help guide stem cells in the brain and other organs to repair damage.
• Telocytes are an exciting area of research for regenerative medicine and the treatment of neurodegenerative diseases. They offer a unique opportunity to intervene in the communication networks that govern tissue health and repair.

观察到了什么？ (引言)

• 在过去的十年里，我们对细胞间通信的理解飞速增长。以前，细胞之间的通信仅限于简单的激素或局部信号交换。
• 科学家们发现细胞使用外泌体等细胞外囊泡系统，这些囊泡可以携带各种小分子和大分子，如RNA、DNA，甚至整个细胞器来调节细胞功能。
• 细胞之间的电信号交流曾被认为仅限于神经系统中的神经递质。然而，现在发现大多数细胞（无论是哺乳动物还是其他生物）都通过生物电系统进行通信，这些系统控制许多生命过程，如生长、分化和组织修复。
• 一种新型的细胞——称为**天线细胞**（telocytes）——被发现。这些长而细的细胞利用电、化学和表观遗传机制，包括外泌体交换，来协调组织和器官内不同类型细胞之间的活动。

什么是天线细胞？

• 天线细胞是专门的细胞，它们在其他细胞之间充当通信枢纽。它们非常长且细，具有伸展出来并与其他细胞接触的长臂。
• 每个天线细胞都有一个小的细胞核和长而纤细的臂，称为“足突”。这些臂上有一些称为“足点”的地方，包含蛋白质合成所需的机器。
• 天线细胞的长臂帮助它们通过电信号、化学交换以及通过细胞之间传递外泌体（微小的分子包）来进行通信。

天线细胞如何与其他细胞通信

• 天线细胞通过与附近的细胞（如平滑肌细胞、免疫细胞和干细胞）交换信号来调节细胞行为，如生长、修复和免疫反应。
• 当目标细胞受损（例如血管）时，它会发出化学信号，如血红蛋白。天线细胞吸收这些信号并“重新编程”自己，以便做出适当的反应，通过合成蛋白质来修复损伤。
• 天线细胞还可以与免疫系统的细胞互动。例如，当目标细胞是免疫细胞（如巨噬细胞）时，通过外泌体转移设置的天线细胞机械装置有助于调节免疫反应。

外泌体和天线细胞

• 外泌体是携带重要信息的小囊泡，在细胞之间传递信号。天线细胞在接收和发送外泌体方面起着关键作用，这些外泌体携带各种分子，包括蛋白质、脂质、RNA和其他重要的细胞信号。
• 通过吸收来自附近细胞的外泌体，天线细胞重新编程自己以处理特定任务，如组织修复或免疫调节，而不需要发送长距离的信号。
• 这种细胞之间交换外泌体的过程类似于神经系统中突触的通信过程，其中信号在神经元之间传递。

天线细胞和体积传输

• 体积传输（VT）是一种通信方式，信号分子（如神经递质或激素）通过细胞外液（ECF）扩散，并影响目标细胞。
• 天线细胞参与体积传输，因为它们可以通过外泌体等细胞外囊泡来释放和接收信号，这有助于在组织内传递信号。
• 细胞外基质（ECM），即一组蛋白质和其他分子，帮助形成这些信号在细胞间传递的路径。天线细胞在塑造这些路径方面发挥作用，从而使信号能够有效传播。

天线细胞在大脑及其他地方的作用

• 天线细胞广泛分布在许多组织中，包括大脑，它们与神经干细胞、血管和神经纤维相互作用。
• 在大脑中，天线细胞可能帮助创建体积传输的细胞外路径，使信号能够更加有效地传播，比如在脉络丛和脑膜等区域。
• 这些细胞还帮助指导干细胞在大脑和其他器官中的迁移，以修复损伤。例如，位于脑室区的天线细胞可能帮助干细胞迁移到嗅球区域。

天线细胞与神经退行性疾病

• 神经退行性疾病（如阿尔茨海默病和帕金森病）涉及多种过程，包括异常蛋白的积累、线粒体功能障碍和突触连接丧失。
• 天线细胞可能在这些疾病中发挥作用，通过调节神经干细胞以及维持大脑的整体健康。
• 研究表明，脉络丛中的天线细胞可能帮助清除异常蛋白（如淀粉样斑块），这在阿尔茨海默病等疾病中非常重要。
• 未来，天线细胞可能成为修复或再生大脑组织的治疗靶点，因为它们在协调细胞间通信和修复过程方面起着关键作用。

结论

• 天线细胞是一种在细胞通信和组织修复中发挥至关重要作用的细胞。它们通过电、化学和表观遗传信号（包括外泌体交换）来协调其他细胞的活动。
• 这些细胞参与体积传输，并帮助形成细胞外路径，使信号能够在组织间传递。它们还帮助指导干细胞在大脑和其他器官中修复损伤。
• 天线细胞是一个令人兴奋的研究领域，具有再生医学和神经退行性疾病治疗的巨大潜力。它们提供了一个独特的机会来干预调控组织健康和修复的通信网络。