Personal Medical System - Capabilities
Image from Steve Bowers


Medicytes Internal medisystems are comprised of colonies of specialised microscopic machinery distributed throughout their host's body, often comparable in mass to that of the host's natural biological flora. The individual medicytes are highly varied in design ranging from large (>20 micrometre diameter) blood circulating breeds to sub-micrometre devices that reside inside of cells. The range of types and capabilities is too vast for this summary however a broad description of their operations includes: monitoring for invasive pathogens and destroying any found, identifying disruptions to metabolic processes (extra- and intracellular) and correcting them through the targeted degradation/synthesis of relevant biomolecules, sequencing live genomes and correcting any errors (compared to an average template generated from at least 3 sequences randomly sampled from different cells), guiding cell behaviour to remodel tissues, and generally regulating homeostatic processes.

Medicytes use molecular tape to store their instructions and encode their behaviour, a typical DNA repair cyte (comparable in size to a human mitochondrion) can contain 5-10 GB of data with larger extra cellular breeds capable of storing orders of magnitude more. Molecular tapes are also the primary means by which medicytes communicate and coordinate. Beyond basic chemical signals used for simple positional tracking and requests medicytes can release synthetic virus-like constructs that contain several tens of kilobytes of data. Surface markers specify the intended recipient (usually a class of medicyte or area of the body) and when the carrier comes in contact with one it binds to their surface and inserts a molecular tape package into a communications pore. For higher bandwidth communication medicytes can directly bind to each other and spool tape through each other's processors. To minimise the risk of communication error or cyber-attack medicytes are prone to programmed-self-disassembly at any sign of potential subversion. As with natural apoptosis this more often than not leads to unnecessary losses of medicytes, but is a common safety feature. For further anti-malware defence most medisytems add layers of encryption and authentication to their communication protocols; this decreases the chance of an attempted hack both succeeding and remaining undetected at the cost of reduced overall system performance caused by increase coordination time and energy. Exactly what users optimise their medisystems for depends on the hazard level of their environment.

Stimplants In addition to circulating and tissue-residing medicytes personal medical systems include a comprehensive network of macroscale implants. Typically clustered around sites of clinical significance (such as organs and major vasculature) these specialised implants monitor their environment and "stimulate" healthy function. Consequently known as stimulants they are the backbone of any medisystem; usually on the order of a few centimetres in any dimension an average baseline human may possess dozens of stimplants.

In addition to their diagnostic and therapeutic role stimplants are responsible for synthesising new medicytes. Whilst some medicyte types are capable of self replication manufacture by stimplants is safer, faster and more energy efficient; largely due to their far greater relative size and specialised fabrication clusters.

Ultratech networked immunity Whilst not a physical component of medisystems bionts in the major empires often benefit from maintaining a constant communication link to the local ruling transapient. Remote supervision of a medisystem by ultratech software significantly increases its capability to defend against infections from synthetic sources; be they physical attacks by rogue technocytes or digital subversion of the medisystem (though at the molecular level the distinction is moot). Bionts generally do not experience any improvement in regenerative capability as their physiological systems would already have been optimised for their biology but novel synthetic pathogens are a serious threat. With an link to ultraware swarms of balkanised medicytes can emergently coordinate to an exceptionally high degree, continually but safely mutating to increase the chances of detecting pathogenic technocytes and provide a resistance through diversity against subversion.

Networked immunity of this kind is just one part of the many defences advanced areas of the terragen sphere have against technocyte infection. In many places universal surveillance and smart matter in the environment can detect and prevent the deliberate or accidental creation of such risks long before they arrive. But in the rare circumstances where these systems fail (or when a hostile external power bypasses them) supervising ultraware provides another layer of protection for bionts.

When leaving an area with this type of provided service (for example: when voluntarily entering a high-hazard region) the more advanced medicytes persist for a few hours before safely disassembling once complications in complex coordination arising from lack of hyperintelligent oversight become significant.


Rapid Tissue Regeneration Most cases of bodily repair by medisystems are handled by the facilitation of natural regenerative mechanisms; stimulation of natural immune cells, digestion of toxins, regulation of cell behaviour via intracellular cytokines etc. In cases of more significant damage a medisystem can build new tissue in situ. Free-floating medicytes are recruited to the affected area where they synthesise penetrating fibrils and bond together to form a mycelia-like structure. The fibrils proliferate to create an artificial extra-cellular matrix with some components safely breaching cell membranes for cytoplasmic regulation. Dead and dying cells along with any debris are absorbed by the scaffold which uses the material to grow denser. Surviving cells are stimulated to proliferate at accelerated rates while being directed along the scaffold to take their correct position and assume their intended function. Where possible medicytes embedded in the matrix will make up for any loss-of-function due to the damaged tissue. For example; damage to an organ such as the liver will result in the growth of blood-filtering medicyte clusters that will connect up to local vasculature, bypassing the affected area. As this scaffold grows to fill the entire damaged area it rapidly synthesises replacement tissue, creating many biological materials from scratch as well as recruiting rapidly dividing cells from nearby tissues.

The speed of regeneration can vary depending on the wound and the medisystem however a typical scaffold can cultivate healthy tissue at a rate of 1mm per hour. The loss of a significant quantity of body mass, such as a severed limb, can be replaced by a layer of scaffold that will appear to ride on a rapidly growing limb.

If mechanical support or manipulation is needed (e.g. to repair a broken bone) a medisystem can quickly assemble in vivo splints. Specialised toroidal medicytes cluster in surrounding vasculature and attach to the epithelial lining. There they can expand or contract, widening or narrowing the vessel. By connecting to each other these medicytes can massively increase the stiffness of the vessel and by working in tandem with those in other vessels can apply pressure across tissues. Whilst this can lead to vessels being damaged (including bursting entirely) it is usually worth it.

Body Modification Owing to the sophistication of medisystems it is simply a matter of programming to allow a medisystem to alter the host's bodily attributes and appearance. Basic phenotypic tweaks include changes to height, weight, body fat/muscle percentage and distribution, skin tone/colouring, eye colour, bone structure, facial proportions, hair colour and length, natural odour, body shape, secondary sexual characteristics and many more. For cosmetic reasons it is common for medisystem users to parameterise their desired physical characteristics. From then on their system will act to keep their body within optimal conditions.

Beyond this radical tweaks are possible but often require the installation of genemods and an iterative process of guided tissue differentiation and development. Autodoc modification (or simply destructive upload followed by engeneration) is faster but many sophonts enjoy the experience of transitioning sex, race and even clade. The most radical of changes can take months to complete and require multiple intermediate forms, for example: if changing from air to water breathing an amphibious stage must be endured.

In most major empires sophonts regularly use bodymods to match the current vogue. Indeed when travelling between cultures it is common for bionts to download not only local immunity protocols but to also run their phenotype through a Cultural Beauty Optimiser and take on the recommended bodymods. Some sophots take such things quite seriously and are constantly altering their body forms to match the style of the hour.

Contraception and Reproduction Personal medical systems can easily prevent pregnancy using a variety of techniques with minimal or no side effects, regardless of the sex of the sophont. Whilst in-built contraceptive ability is common in bionts thanks to historical genemods, amongst sophonts lacking the appropriate tweak medisystem contraceptive is quite convenient.

If an individual does wish to reproduce sophisticated medisystems can infiltrate the uterus/egg and integrate with the developing foetus. Growing along with the developing offspring this nascent medisystem will provide pre-natal care and ensure that the child is born with their own personal medical system fully integrated. In the case of hopeful parents with incompatible genomes (even within clades personal choices in genemods can cause lethal conflicts) a medisystem can attempt to compile a viable compromise. However this process carries risk, particularly in inter-clade relationships. Most personal medical systems are programmed to err on the side of caution and will prevent pregnancy if it is unsure of a viable genome. If errors are found in a developing foetus the medisystem can safely abort it or place it into biostasis until expert help can be obtained (this often requires transplantation to an artificial womb and total genome modification).

Biostasis As any interstellar traveller knows medisystems are capable of interfacing with simple supplementary equipment to safely transition their host into a state of suspended animation known as biostasis. Safer and less energy intensive than cryogenic freezing biostasis virtually halts all metabolic activity, inhibits decomposition at a molecular level and suspends all conscious thought all while keeping the body at ambient temperature (though for extra safety the environment is usually marginally above the freezing point of water). To safely lower the host into biostasis a medisystem first begins a process of breeding the specific medicytes and nanites it will require (these may be provided exogenously via a premade infusion) which the host can be conscious for if desired. As their numbers rise these specialised machines spread into every cell in the body and iteratively shut down metabolic processes, this is often achieved by nanites binding to protein based molecular machinery to inhibit its activity. Medicytes absorb or release factors as needed to limit negative reactions.

As the metabolic shutdown continues the next phase begins. Chemical fixatives are flushed through the circulatory system as well as being synthesised on site by medicytes embedded in various tissues. IV connections to supplementary equipment siphon water from the body to balance out volume. The cocktail of fixatives is comprised of small polymers with two reactive ends that serve to bind biomolecules together. In this fashion at the biochemical level the body is highly crosslinked, locking sub-cellular structures in position. Before this phase reaches completion cryoprotectant and buffer solutions are infused into each cell to further prevent molecular disruption.

Biological functions are not completely ceased in this state as low level repair must still continue but the bulk of such work is directly performed by medicytes. Few signs of life are superficially detectable at this stage with even pseudo-heartbeats occurring less than once per minute to slowly transport material through the sluggish circulatory system. In the current era modelling predicts that an average biont can remain in a biostatic state for over a thousand years before accumulated damage reaches a level that necessitates raising the body to a higher metabolic level for repairs (though the sophont may still be kept unconscious). Awakening takes place over many days as the phases are carefully reversed with the medisystem meticulously detecting and healing any damage as well as carefully balancing hormone, salt, glucose and other important homeostatic levels.

In drastic situations where a medisystem predicts that damage to the body is too severe with tissues dying faster than they can be regenerated an emergency biostasis procedure can be attempted. Lacking sufficient preparation time and supplementary equipment such processes inevitably cause significant additional damage to the body, prioritising the preservation of the central nervous system and vital organs first. Recovered wounded in this state are often submersed in liquid nitrogen when placed into autodocs to prevent further damage and allow comprehensive, gradual surgery without the risk of further decay. The success rate for emergency biostasis is not high and many sophonts choose to alter their medisystem triage protocols to enjoyably euthanise them in such states instead, content to be restored from an implanted mindstate backup. Others more attached to their physical body maintain additional stimplants that contain prepared biostasis therapeutics, at the cost of increased caloric input.

Lazarus Procedure A rare feature present in some transapient designed/networked medisystems is one that allows dead sophonts to be resurrected in situ. In properly angelnetted societies medisystems capable of performing Lazarus procedures are unnecessary; firstly because such trauma is unlikely to occur to an individual and secondly rescue and recovery are far more efficient. Even in some societies without angelnets most sophonts have other options such as transmitting their mindstate to an Engenerator or otherwise relying on backup recovery. Consequently medisystems capable of performing Lazarus procedures are mostly seen in partially angelnetted societies in the Middle Regions, though they are popular with semperists everywhere. Depending on whom you ask these individuals are either prepared or paranoid.

If the damage to the host is too great the resident medisystem will euthanise the user, ensuring that their backup implant has an up-to-date mindstate copy. In conjunction with this mycelial smart matter will be released that will begin digesting the host body. Rapidly growing the mycelium bursts through the skin and forms a diamondoid cocoon. Biomass is recycled to construct the machinery necessary for engeneration; if insufficient materials are present the cocoon can grow branching roots that attempt to harvest material from the environment. In the unlikely scenario the Lazarus procedure is invoked due to a fatal infection the disassemblers will attempt to destroy the pathogen. If this cannot be done (e.g. the host is suffering attack from malicious technocytes) the pathogen will be encapsulated in layers of diamond and sacs containing chemicals for highly exothermic reactions. The cocoon can then eject the capsule (in a manner akin to a ballistic weapon) simultaneously breaking the sacs and heating the capsule to extremely high temperatures.

Within the cocoon a new body is grown for the host over a period of a few days. During this process the the host can even be instanted in a virch to overview the construction of their new body. This has led to some unexpected consequences with some users invoking Lazarus procedures simply for radical cosmetic purposes.

Example treatments

Personal Medical System Immune Response
  • Upon encountering a foreign agent (virus/bacteria/toxin/nanite) the components of the medisystem will execute responses according to the severity and nature of the threat. The average medisystem deals with infection on a regular basis but nearly all such infections are dealt with long before the host notices. Broadly these responses involve:
  • Detection of the agent: this process occurs through a variety of mechanisms. Initially chemical sensors detect the presence of various soluble factors either released by the agent or created by various warning devices constantly released by medisystems. This allows immune medicytes to migrate towards an infectious agent, effectively 'sniffing' them out. For physical detection and latching immune medicytes are covered with millions of fibres, the tip of each fibre is coated with a different 'grip' molecule that is designed to bind to different types of antigen (but not be able to bind to human tissue). Upon binding a fibre activates a signalling pathway inside the medicyte allowing it to determine which type of grip has bound to the pathogen. The majority of fibres are then reconfigured to similar grips (though not all in case other antigens might be found) with mutation/selection of fibres rapidly evolving the best grip. All the while the bound fibres contract in an attempt to pull the agent into the medicyte in a manner akin to phagocytosis (if the agent is too large multiple medicytes can bind together to produce a 'giant multibot'). Once inside the agent is encapsulated in a disassembly capsule where it is atomically disassembled providing a highly detailed profile that is transmitted to the rest of the medisystem (and through the DNI to medical libraries on the Net).
  • Using the profile a medisystem can enact appropriate protocols to get rid of the foreign agent. This is a two-step process involving the synthesis and release of targeted delivery systems (carrying antibodies, antibiotics, antivirals, antirobotics, synth-phages etc) designed to make the host's body toxic to the agent. Most immune medicytes will become microvorous (leaving some to continue disassembly so as to catch different agents that may be present). Agents are phagocytosed into the medicytes where they are encapsulated before being assaulted by whatever regimen best destroys them e.g. changing the temperature, pH, pressure, composition, applying electricity or even using appropriate grip fibres to tear the agent to pieces. Invariably a combination of destructive techniques is used to speed up throughput; the waste products are then converted to non-toxic particles and released in vesicles that can be picked up by medicytes tasked with clean-up.
  • Once the infection has been dealt with a medisystem can upload the technique to medical libraries on the 'net to be downloaded in updates to other sophont's personal medical systems. This establishes a system of networked immunity in a population, where many individuals gain immunity from a disease if just one person manages to fight it off.
  • To protect surrounding tissues from damage prophylactic medicines (appropriately prescribed based on the agent's profile) are administered. If needed quarantining of diseased tissues through rapid fibrous encapsulation can occur.
  • A regenerative scaffold is synthesized in damaged tissue and regenerates the tissue through absorption/regeneration (this process occurs in tandem with fighting infection). If nutrient supply is insufficient the medisystem can cause the host to feel strong cravings for certain foods. For this purpose customised nutrient broths can be prescribed by the controlling subsentient program (orders can even be sent directly from to household assemblers). Occasionally the heat produced by a regenerative scaffold may result in the host becoming temporarily feverish (though nerve-interfacing components can remove any feelings of discomfort).
  • In emergency situations: quarantining affected area and sacrificing tissue to save key organs. Medisystems can then fight infection using far more destructive "scorched-Earth" strategies (utilising corrosive chemicals, burning/electrifying infected tissue) that can greatly damage host tissue. Over time if the damage is not reversed key organs will be sacrificed in order of importance with protecting the brain remaining paramount. If this too fails most medisystems are capable of attempting emergency biostasis. Some medisystems are even capable of initiating bailout or Lazarus procedures (ultratech only).
  • For unprecedented infections: in response to foreign agents personal medical systems compare the profile of the agent to a medical library that has limited capability to innovate a response. There is danger to innovative responses as untested medical regimens can have disastrous side effects. If the medisystem cannot fight the infection more sophisticated medical facilities may be required. If these facilities are not available (or against the host's wishes) the medisystems can switched to scorched-Earth strategies although these procedures involve great discomfort. Some medisystems include compubone augmentation to give huge computational power to simulate and design new regiments, if available computational resources across the Net along with dedicated AI can be combined with the host's efforts. Unfortunately due to the incredibly high number of variables in a host's biology this technique is not fool-proof but is much more successful than scorched-Earth strategies. If the battle seems lost, emergency procedures are enacted such as upload into a memory box (unnecessary if the sophont is fitted with a suitable DNI and backup) or bailouts or Lazarus procedures by ultratech systems.
Personal Medical System Trauma Response A medisystem trauma response is strongly determined by the nature of the trauma. Broadly these responses involve:

  • Detection of the trauma through chemical, ultrasound, micromechanical sensors.
  • Synthetic clot response to limit damage (also activates medisystem immune response). Even major wounds can be clotted in seconds.
  • If necessary (e.g. if the wound is a large gash or a limb is broken) medicytes located on the skin will rapidly (within minutes) spray tough protein fibres (harvested from the host) over and around the wound to form a protective cast.
  • A regenerative scaffold is synthesized in damaged tissue and regenerates the tissue through absorption/regeneration. If nutrient supply is insufficient the medisystem can cause the host to feel strong cravings for certain foods. For this purpose customised nutrient broths can be prescribed by the medisystem's governing subsentient (orders can even be sent directly to household assemblers).
  • If the heat produced by a regenerative scaffold results in the host becoming temporarily feverish (though nerve-interfacing components can remove any feelings of discomfort).
  • Medicytes in tissue severed from the body will enact different protocols to place the tissue in stasis. Partial scaffolds are grown on the surfaces previously connected to the body. In this form the tissue can be placed into its original place in the body where the scaffold will bond it back in, the tissue can then be regenerated. This option is useful in situations such as the severance of a limb as the sophont can simply pick the limb back up and reattach it, saving far more energy and time than waiting for the limb to regrow.
  • In cases of severe trauma; scaffold will redirect most blood flow from the damaged tissue and, where necessary, medicytes/scaffolds will replace the function of the damaged tissue (e.g. skin medicytes will rapidly replicate and stretch to provide a protective covering)
  • In cases of terminal decline: quarantining the affected area and sacrificing its tissue to save key organs. Over time if the damage is not reversed key organs will be sacrificed in order of importance with protecting the brain remaining paramount.
  • If this too fails most medisystems are capable of emergency biostasis perhaps extending to the bailout or Lazarus procedures provided by some ultratech medisystems
Personal Medical System Acute Radiation Syndrome Response
  • Detection and quantification of radiation exposure by suitably sensitive stimplants. For nearbaseline and similar bionts doses up to 10 grays initiate a therapeutic response, at greater levels the damage is too extensive and a medisystem swaps to stabilising the host until they can reach an autodoc.
  • Extensive replication and fabrication of medicytes to replace the loss-of-function from the death of certain tissue types. Rapidly dividing cells are more vulnerable to radiation damage, and thus less able to be saved. This includes bone marrow, white and red blood cells, follicular cells and the lining of the gastrointestinal system. For the duration of the treatment these functions are performed by new breeds of medicytes.
  • Cell stabilisation is attempted with vital and vulnerable tissues prioritised. Epidermal tissues are infused with nanites and other molecular machinery to temper the effects of burns, apoptosis is prevented in all but the most severely damaged cells and cell behaviour guided to continue as normal, synthetic platelets ameliorate the risk of internal bleeding.
  • Regenerative scaffolds are grown at the sites of every significantly damaged organ, digesting tissues to far gone to save and synthesising healthy replacements. Due to the high level of synthesis required overall rates are slower than normal with the replacement often taking several days.
  • Whole body genomic repair is performed. Typically the only cells to permanently contain intracellular medicytes capable of DNA resequencing and repair are those with high rates of division. All other cell types are periodically visited by these units, typically 2-4um long these specialised medicytes bind to the outer surface of a cell nucleus and insert polymeric fibres through nuclear pores. Molecular tooltips at the head of each fibre unwind DNA and begin sequencing, waves of conformational change travel up the fibres into the medicyte allowing the sequence to be checked against an internal molecular tape. Any mutations detected are excised and corrected by the same tooltips. The population number of genome repair medicytes grows rapidly in response to radiation, resulting in the whole body of a nearbaseline human being sequenced and repaired over approximately one megasecond (fever is a common side effect during this time due to the waste heat of these medicytes). This is the longest phase and, if successful, is followed by a steady decline in medicyte numbers back to baseline, marking the end of treatment.
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Development Notes
Text by Ryan B
Initially published on 16 October 2011.

updated/expanded by Ryan B, March 2018