Vasculoid Circulatory Replacement System

Artificial Blood

Vasculoid system 2
Image from Steve Bowers
The vasculoid system consists of a lining of artificial cells which use cilia to transport particles such as respirocytes to various parts of the body, with no need for a heart or other pump.
First proposed in the Information Age by Robert Freitas and Christopher Phoenix, a Vasculoid circulatory system is a form of artificial blood which transports resources around a biont body without the need for a heart or other pump.

Whilst the idea of a vasculoid existed during the information age the complexity of not only designing one but designing one that integrated seamlessly with the body pushed it far beyond the realm of the then current science. The human body, like other biont bodies, relies on many characteristics of the circulatory system and the pumping action of the heart, and efforts to emulate and/or change those characteristics ran into many technical problems.

It wasn't until the late First Federation age that medical science and bionanotechnology were mature enough to design a system that was capable of being implanted with all the benefits whilst remaining free of side-effects. Some early methods included the synthesis and release of smart drugs via nanoparticle delivery systems by the vasculoid to alter cell/tissue behaviour so as to compensate for the change in microenvironment(*) as well as inbuilt mechanisms to replicate standard vascular behaviour(**). Later more advanced technologies allowed subtle genemods to be developed that would alter the subject's body so as to make the vasculoid a necessary functioning organ, even more sophisticated genemods and bioengineering allowed subjects to grow their own sophisticated vasculoid as part of their body's normal function.

There are many different designs of vasculoid system, but they all consist of an active, controllable lining which coats the surface of all blood vessels, equipped with cilia capable of wafting fluids, encapsulated materials and devices through the fluid-filled vessels to any part of the body.

Vasculoid systems consist of trillions of individual plate-shaped devices, generally about 1 micron thick and two square microns in surface area which bond together at the edge. Early designs consisting largely of sapphiroid were problematic, and most modern designs are mostly or entirely biological in structure. Most biotech plate designs bond together to form a continuous lining, known as vasculoid tissue, which also helps to maintain and control the extracellular matrix surrounding other cells in the body. Each plate has around twenty cilia, each about 100 nanometres long, which can propel fluid and materials through the system in any direction. These biotech plates either replace the endothelium cells altogether, or mimic their normal environment so that they function as if blood flow and pulse effects were present.

Most materials transported by the vasculoid system are contained in specialised structures, respirocyte capsules containing gases and larger ones containing complex molecules. Wastes from the cells are also transported in these containers, and the contents are identified by rewritable tags on the outside surface. Other items that are transported in the vasculoid system include many types of technocyte which carry out repair and immune response functions. Red blood cells are not necessary for oxygen transport when a vasculoid system is operating, and production is inhibited to less than 1% of normal rates. White blood cells of many kinds, including several neocyte forms, are actively transported to sites where they are required, or permitted to move freely when necessary.
An active lining for the lymphatic system may also be used in conjunction with the blood-vasculoid system, or may be used by itself.

Most vasculoid systems use biotech replacements for red blood cells. Often these are functionally similar to naturally occurring red blood cells, but in advanced systems hi-tech devices known as respirocytes may be used. Respirocytes are containers filled with gases at pressures of up to 1000 bar, requiring specialised docking cells for both loading and unloading. Because the vasculoid system carries the same amount of material as natural blood but in a more compact form, this leaves a large volume of the blood system unused, and this volume may be filled with additional technological resources, such as additional processing capacity, reserves of oxygen or nutrients, devices for physical or neurotechological augmentation, data storage, even weapons or smuggled materials. It is possible to convey an entire inactive vasculoid system within this unutilised volume, enabling a user to pass the system on to one other biont of similar stature.

A biont using a vasculoid system has improved resistance to shock and blunt force trauma due to the mechanical stiffness of the vasculoid lining; wounds can be sealed almost instantly and the system will continue to operate, even inside a detached limb. Additional oxygen reserves can be stored in the system, up to 100 minutes of supply if necessary. Rapid dissipation of heat can reduce trauma due to localised heating. External ports allow the quick introduction of replacement vasculoid devices and of many other useful resources. Some advanced designs incorporate small amounts of Ultimate Muscle within the vasculoid tissue, allowing the user to augment their physical strength to a certain extent. Most designs incorporate independent control systems which interface with the nervous system at various points, and with external devices if required; in many cases this control system may be used as a high-bandwidth communication channel between the user and external devices.

Usually there are few external indications that a biont is using a vasculoid system; the biont has no need for a heartbeat or pulse, but both can be simulated if necessary. In fact a simulated pulse effect is standard in most designs, a feature which helps to maintain the wellbeing of the cellular and extracellular environment in surrounding tissue. But the fact that a vasculoid system allows a user to go without breathing for extended periods and survive a wide range of severe injuries makes this equipment popular among bionts who engage in high-risk activity.

(*) - By releasing siRNAs or other factors that influence gene expression and thus cell behaviour without the "normal" stimuli. If a pulse effect is not present the vasculoid system will monitor cell behaviour and release factors to control the behaviour directly.

(**) - An example of this is facilitating diffusion between the vasculature and surrounding tissues and/or having mechanisms to allow cell migration.
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Development Notes
Text by Steve Bowers and Ryan B
Initially published on 29 August 2012.

Additional Information
Adapted from Robert Freitas' essay 'Vasculoid: A Personal Nanomedical Appliance to Replace Human Blood'