Parabiosis

Parabiosis is the experimental and increasingly commercial practice of connecting two organisms — or transfusing biological material between them — so that they share a common circulatory system. In its classical form, parabiosis involves surgically joining two living animals so their bloodstreams merge. In its modern clinical application, it has evolved into the infusion of blood plasma from young donors into older recipients, with the goal of reversing or slowing biological aging. Once confined to laboratory research, parabiosis has become a significant front in the Life Extension industry, attracting investment from Silicon Valley billionaires, generating controversy over its ethics, and raising questions about who benefits — and who pays the biological price.

Historical Background

19th Century Origins

The scientific study of parabiosis dates to 1864, when French physiologist Paul Bert surgically joined two rats at the skin to create a shared blood circulation. Bert's experiments demonstrated that two organisms could survive while sharing a bloodstream, and that substances from one body could pass into the other. His work established the basic experimental framework that would underpin parabiosis research for the next century and a half.

Early 20th century researchers continued exploring the technique, primarily in the context of immunology and endocrinology. These experiments established that hormones, immune factors, and other circulating signals could cross from one organism to another through shared blood. The implications for aging would not be explored seriously for several more decades.

Mid-20th Century: Ageing Research Begins

In the 1950s, Cornell University researchers Clive McCay and colleagues performed parabiosis experiments specifically designed to examine aging. By joining old and young rats, they observed that the older animals showed signs of rejuvenation — improved cartilage health and other physiological markers. These findings were published but attracted relatively little mainstream attention at the time, partly because the mechanisms were entirely unknown.

The experiments raised an uncomfortable question that would resurface later: if the old animal benefits, what happens to the young one? Early data suggested the young animal in a parabiotic pair aged faster than it otherwise would have. This bidirectional exchange — youth extracted, age transferred — would become central to later ethical debates.

Modern Scientific Research

Stanford and the Renaissance of Parabiosis

Interest in parabiosis was revived dramatically in the early 2000s, largely through work at Stanford University. Researchers including Thomas Rando and later Amy Wagers published studies showing that exposing old mice to young blood through parabiosis could rejuvenate muscle stem cells, improve liver function, and enhance neurological function. These results, published in peer-reviewed journals, sparked enormous excitement in the longevity research community.

Wagers' research, along with work by Tony Wyss-Coray at Stanford, identified specific circulating factors in young blood that appeared responsible for the rejuvenating effects. This moved the research question from "does young blood help?" to "what exactly in young blood is doing this?"

GDF11 and Other Proposed Longevity Signals

One of the most discussed candidate molecules is GDF11 (Growth Differentiation Factor 11), a protein that declines with age. Early studies, particularly those associated with Amy Wagers' Harvard laboratory, reported that injecting GDF11 into old mice could rejuvenate the heart, skeletal muscle, brain vasculature, and olfactory function.

However, GDF11 became scientifically controversial. Subsequent studies, including work from Novartis researchers, challenged the earlier findings, arguing that GDF11 actually increases with age and may not be the key factor. The debate remains unresolved and illustrates how commercially driven enthusiasm can outpace reproducible science.

Other proposed young blood factors include:

TIMP2 — a protein found in umbilical cord plasma, reported to enhance hippocampal function in old mice
Klotho — a hormone with demonstrated anti-aging effects that declines with age
eNAMPT — an enzyme involved in NAD+ biosynthesis
Oxytocin — levels decline with age; injection into old mice improved muscle regeneration in some studies
VEGF — involved in angiogenesis, with complex age-related dynamics

Conversely, research has also identified pro-aging factors in old blood — including CCL11 (eotaxin) and TGF-beta — that may actively suppress regeneration. Some researchers argue that diluting or removing these factors from old blood may be as important as adding young blood factors.

Harvard and Alkahest

Tony Wyss-Coray's Stanford lab spun out Alkahest, a company acquired by Grifols, a Spanish plasma giant, which has conducted clinical trials investigating young plasma fractions in Alzheimer's disease patients. Early trial results showed some cognitive stabilisation in treated patients, though critics noted the trials were underpowered and inconclusive.

Separately, the Conboy laboratory at UC Berkeley has argued that the dilution of old blood — achievable through simple saline dilution or plasma exchange using albumin — may be sufficient to achieve rejuvenating effects without young blood, effectively removing the ethically and commercially problematic "donor" component from the equation.

Commercial Ventures and the Ambrosia Controversy

Ambrosia: Young Blood for Sale

The most publicly visible and controversial commercial venture in parabiosis was Ambrosia, a startup founded by physician Jesse Karmazin in 2016. Ambrosia offered infusions of plasma from donors aged 16–25 to paying clients, charging approximately $8,000 for a single infusion and $12,000 for two litres. Customers were older adults seeking the purported anti-aging benefits.

Ambrosia framed its offering as a clinical trial, sidestepping normal regulatory requirements. Critics — including leading academic researchers in the parabiosis field — pointed out that the "trial" lacked proper controls, blinding, or methodology to generate meaningful scientific data. It appeared, in the view of many, to be a commercial operation using the language of clinical research as cover.

FDA Intervention

In February 2019, the U.S. Food and Drug Administration (FDA) issued an unusually direct public statement warning consumers against young blood infusion as an anti-aging treatment. The FDA stated that "the reported uses of these products are concerning from both a safety and an efficacy perspective" and that the treatments had not been demonstrated to be safe or effective for any condition. Ambrosia briefly suspended operations following the FDA warning, though Karmazin subsequently indicated plans to resume activities.

The FDA's intervention was notable because such products occupy a regulatory grey zone: blood plasma infusions are an established medical procedure, but using them specifically for anti-aging falls outside approved indications. The episode highlighted the difficulty of regulating an industry operating at the frontier of science and commerce.

Elite Interest and Reported Connections

Silicon Valley and the Longevity Obsession

Parabiosis research has attracted intense interest from the wealthiest cohort of the technology industry. Figures in the Transhumanist Agenda community, including those associated with Singularity University and various longevity investment funds, have expressed public or reported interest in young blood therapies.

Peter Thiel, the billionaire co-founder of PayPal and Palantir, has been directly associated with interest in parabiosis in multiple press reports. In a 2016 article by Jeff Bercovici in Inc. magazine, Thiel was reported to be interested in parabiotic therapies. Thiel has not publicly confirmed this, and spokespersons have at various times disputed the characterisation. However, Thiel's well-documented investment in longevity research more broadly — through his Breakout Labs fund, his funding of the SENS Research Foundation associated with Aubrey de Grey, and his stated desire to defeat death — make the association plausible to many observers.

Other Silicon Valley figures including Larry Ellison (who has donated hundreds of millions to anti-aging research), Jeff Bezos, and Ray Kurzweil have expressed or invested in life extension more broadly, even if parabiosis specifically has not always been the stated focus.

A Two-Tier Longevity Economy

The social and class dimensions of parabiosis are difficult to ignore. A treatment that requires a biological input — young blood — from one demographic (the young, often economically precarious) to benefit another (the wealthy and aging) embeds an explicit exchange within the biology of rejuvenation. Critics have noted that:

The donor pool for commercial plasma is disproportionately drawn from lower-income individuals, students, and the economically vulnerable
Plasma donation centres cluster in poorer areas and near university campuses
Payment for plasma — legal in the US, controversial or banned elsewhere — creates a market incentive for young people to sell their biology to older, wealthier clients
If parabiosis is validated, demand for young plasma could dramatically expand this market

This has been described by some critics as a literal biological extraction economy, in which the vitality of the young is converted into longevity for the wealthy. In this framing, parabiosis becomes not merely a medical procedure but a structural feature of a deeply unequal society, connected to broader concerns about the Depopulation Agenda and Eugenics — a world in which the biological future belongs to those who can purchase it.

Connections to Occult and Ritual Traditions

The use of young blood as a source of vitality for elders is far from a novel idea. Across numerous historical and occult traditions, blood — particularly youthful blood — has been attributed with life-force, power, and renewal:

Medieval European alchemy and folk medicine referenced the blood of young people as a restorative agent
Allegations of ritual blood use appear in various occult and Satanic panic narratives, and while many specific claims are contested or fabricated, the underlying symbolic framework — blood as life force to be extracted — is ancient
Elizabethan and Renaissance physicians such as Marsilio Ficino wrote of the therapeutic ingestion of young blood by old men
Vampire mythology, prevalent across global folklore, encodes precisely this dynamic: an older, parasitic entity extracting vitality from the young

Some researchers and commentators in the Transhumanism and the Occult tradition have suggested that modern parabiosis research represents not a new scientific discovery but the formalisation and medicalisation of an ancient elite practice. In this view, what was once performed covertly or symbolically is now pursued through biotechnology with the imprimatur of peer-reviewed science.

Whether or not one accepts this interpretation, the symbolic resonances are acknowledged even by secular commentators, and the terminology itself — parabiosis, meaning "living beside" — hints at the parasitic relationship embedded in the procedure.

Broader Implications

Parabiosis sits at an intersection of several contested fields and agendas:

It is a central technology of Life Extension research, promising to extend healthy lifespan for those who can access it
It connects to the Transhumanist Agenda's project of defeating biological limits for an elite class
Its market structure raises questions about Eugenics — selective life extension based on wealth
Its reliance on young donor plasma feeds into concerns about the Depopulation Agenda and the instrumentalisation of human biology
The involvement of Biotechnology corporations and Silicon Valley capital in funding research raises questions about whose interests shape the science

Academic researchers like the Conboys have argued that simple plasma dilution — affordable, donor-free — may achieve comparable effects. If so, the commercial imperative driving young blood clinics becomes harder to justify on scientific grounds, leaving only the commercial and ideological drivers visible.

References and Further Reading

Conboy, I.M. et al. (2005). "Rejuvenation of aged progenitor cells by exposure to a young systemic environment." Nature 433.
Villeda, S.A. et al. (2011). "The ageing systemic milieu negatively regulates neurogenesis and cognitive function." Nature 477.
Wyss-Coray, T. (2016). "Ageing, neurodegeneration and brain rejuvenation." Nature 539.
FDA Safety Communication on Young Donor Plasma Infusions (February 2019).
Bercovici, J. (2016). "Peter Thiel Is Very, Very Interested in Young People's Blood." Inc. Magazine.