Dr John Dunphy, who is under investigation by the Irish Medicines Board (IMB) for providing the treatment at his clinic in Carrigaline, Co Cork, said 400 patients, all from Britain, were due to be seen over the next four weeks.
"All of them had paid for their flights and hotels, and now they must all cancel. There is a major loss financially to people who can ill afford it," he said.
Dr Dunphy had to suspend his use of stem cell therapy a treatment which is not licensed by the Irish Medicines Board since the signing into domestic law on April 7 of new EU regulations.
The GP, who used stem cells supplied by Swiss company Advanced Cell Therapeutics, also claims he is the victim of an orchestrated campaign by British neurosurgeons annoyed at losing patients to him.
In an interview in the Irish Medical Times, Dr Dunphy defended his use of the therapy, used mainly to treat multiple sclerosis and spinal injury.
He said all stem cells he used were:
Derived exclusively from umbilical cords (no right-to-life issues).
Donated by informed consent.
Tested for infectious diseases HIV1, HIV2, Hep B, hepatitis C, syphilis and CMV (herpes virus).
Traceable from donor to recipient.
Used to treat 80 different disease types, with clinical benefits reported in over 80% of patients treated.
He said he had decided to speak out now to expose those conducting what he called a campaign of vilification.
"I presume that senior neurologists in the UK were irritated that their patients were coming to Paddyland for advanced therapy."
He said reports about exorbitant costs €30,000 were "total and complete garbage", adding some patients were charged nothing and others between £1,000 and £5,000 (roughly between €1,400 and €7,200).
Dr Dunphy said that by turning its back on stem cells Ireland was wasting an opportunity.
"This is an extremely important field of medicine. If Ireland does not get involved, we are going to lose out, both from a medical and commercial point of view," said Dr Dunphy.
He added that he has applied to the IMB for a licence to administer stem cell treatment under the new EU regulations.
A spokesperson for the IMB said an investigation into the use of stem cell therapy is ongoing.