Banned biological products harvested from human cells are being used in UK beauty clinics, according to experts who warn that the luxury treatments could carry serious health risks.

Exosomes have been touted as the latest “miracle” skincare treatment, with A-list celebrities such as Kim Kardashian seeking their rejuvenating effects and cosmetic clinics offering exosome facials and microneedling for hundreds of pounds a session.

Exosomes are tiny membrane packages containing proteins, lipids and DNA fragments that are released by cells. Many clinics use formulations derived from plant or salmon testicle cells, but some appear to rely on exosomes derived from human umbilical cord blood or other cells, which would be a breach of UK and EU regulations.

“I’m really appalled and shocked. You shouldn’t be having human cell-derived products and [using them] on other humans,” said Dr James Edgar, a cell biologist at the University of Cambridge, who is seeking tighter regulation of the products. “These are human biologics and there’s a risk for disease transmission. It’s not in the public’s interest of safety to have this stuff washing around.”

Edgar, whose research focuses on exosomes, became aware of the issue when his wife was offered an exosome treatment at a hair salon. While exosomes are being widely marketed as a cosmetic remedy for hair loss, acne, eczema and ageing skin, scientists remain uncertain of their primary biological function or exactly what these packages contain. “These things are claimed to have loads of growth factors,” said Edgar. “If you’ve got a melanoma on your face that could be pouring petrol on the fire.”

There is also no reliable way to isolate exosomes from viruses, according to scientists.

Dr Guillaume van Niel, a research director at the Angers Cancer and Immunology Research Centre in Nantes, France, said: “The most dangerous risk would be that viruses are in the product. Viruses have the same size and the same physical properties as exosomes. It’s nearly impossible to sort exosomes out of a pool of viruses. If you isolate one, you get the other.”

There could also be unintended side-effects, he said. “I’ve been working on exosomes for 25 years, I’m one of the pioneers of the field and we still don’t know exactly what exosomes are,” Van Niel added.

An online search revealed several UK clinics appeared to offer treatments involving exosomes harvested from human cell lines.

Alison Miller Skincare & Aesthetics, based in Totnes, Devon, advertised an exosome treatment at £380 for the face or £450 for face and neck, with the clinic website stating that the exosomes “are ethically harvested from consenting human donors” to provide “the most biocompatible form of exosomes which allows us to get the most effective results”. After being contacted by the Guardian, the page was removed from the website and the clinic responded in a text message that it did not offer the treatment.

Elen Rivas Beauty Clinic, which has branches in Belgravia and Marylebone in London, advertises a microneedling treatment at £350 a session or £950 for three sessions using a product called P198 Exohealer, which, based on the Korean manufacturer’s description, is derived from umbilical cord blood stem cells. The clinic did not respond to questions.

Another London-based clinic referred on its website to exosomes “derived from mesenchymal stem cells, typically harvested from bone marrow or adipose tissue”. When contacted, the clinic said that this description had been added in error, that it did not reflect the treatment offered and that it was aware of and “fully compliant with UK cosmetic and medical regulations”.

Dev Patel, who runs Perfect Skin Solutions in Portsmouth, Hampshire, previously offered human-derived exosome treatments, before realising that the products were banned in Europe. Patel said he immediately withdrew the treatment, and now uses an approved product derived from salmon testicle cells. But he believes there are other clinics using human exosomes – potentially unaware of their legal status – and said he was aware of a supplier marketing the products at an industry conference in October.

Patel, a former NHS doctor, would like tighter regulation of the cosmetics industry, which he said was “riddled” with poor practice. “If anyone can set up a company and sell a product, how do you know you’re getting exosomes?” he said. “Can they all afford multimillion-pound manufacturing plants to get five billion things the size of a virus into a bottle? If not, what are you getting?”

A Department for Business and Trade spokesperson said: “Exosomes of human origin are banned in cosmetics that are sold in the UK. We urge anyone who has concerns about the safety of a product to contact their local trading standards department or Citizens Advice.”