Richard Stuart lifts up his cream polo shirt and points to a small scar just below his left breast. 'That's it,' he said. 'They injected me 30 times, right here, straight into my heart.'
Mr Stuart, 64, a retired textiles manufacturer from Florida, reckons the operation performed on him in December 2005 at Bangkok Hospital has given him a new lease of life. The previous year, a sudden heart failure had left him short of breath, unable to walk up a flight of stairs or drive a car. At that time, doctors installed a pacemaker, gave him a drug prescription and told him there was nothing more they could do for him.
Today Mr Stuart says he's more active than he was before his heart failure. 'After the first month and a half [after the operation], I started to feel I was getting stronger. I started cleaning the pool, the yard, the car. All the normal things that you do,' he said.
The operation Mr Stuart credits with his turnaround is a pioneering stem-cell therapy that claims to rejuvenate damaged hearts.
It works by extracting millions of stem cells from the patient's blood - a 250cc sample is enough - then reintroducing them into the heart or arteries. The hope is that the stem cells will turn into blood vessels or tissue, improving circulation to the heart and its ability to pump blood.
Stem cells, known as the body's 'master cells' that can transform and reproduce, have long been touted as potential miracle cures for chronic diseases and disabilities. But ethical objections to the use of stem cells from human embryos, seen as the most flexible type of cell, has cast a shadow over the field in the US, to the dismay of scientists.
Further controversy was stirred in South Korea in 2005 by the revelation that groundbreaking embryonic stem-cell research credited to scientist Hwang Woo-suk had been falsified.
Using adult stem cells, such as those extracted from blood or the bone marrow, skirts this debate. Doctors say it also has the advantage of being from the patient's body, so the cells are unlikely to be rejected when reintroduced into the heart or arteries.
However, the therapy is still in its experimental stage, and the idea of providing surgery to patients on a commercial basis is controversial. Scientists warn that without adequate testing and strict regulatory oversight, patients run the risk of becoming guinea pigs with little or no recourse.
The blood stem-cell technology used on Mr Stuart was developed by TheraVitae, a biotech company based in Thailand and Israel, where the cells are harvested. It began treating its first paying customers in 2004; 180 patients have undergone the therapy. The cells are either directly injected into the heart - Mr Stuart's procedure - or via a catheter through a coronary artery. The surgery usually lasts about two hours.
The company's studies have shown that the majority of patients have reported an improvement in their health, often to a dramatic degree. Of 40 patients who were tracked after their operation, only seven reported no improvement in their condition. Not one has died during the therapy.
Like Mr Stuart, many of those treated were from the US, where stem-cell treatments are restricted to clinical trials at licensed institutes and hospitals. In practice, this means that many cardiac patients are turned away, as they don't match the criteria for the trials. Researchers are also reluctant to accept acute cases who may not survive the length of the trial, which is a crucial first step towards getting regulatory approval.
Just as premium hospitals in Thailand offering conventional surgery are seeing a surge in foreign patients, often via an internet search or personal referral, so the commercial stem-cell therapy market is taking off. Mr Stuart found TheraVitae on Google and contacted the company - over the objections of his cardiologist - after being rejected by US research institutes. 'They wouldn't even talk to me,' he complained.
Some of the factors that give Thailand an edge in so-called medical tourism - internationally trained doctors, low operating costs, modern infrastructure - also make it a good location for developing new biotech procedures. Dr Kitipan Arom, chief cardio-thoracic surgeon at Bangkok Hospital, leads seven US-trained Thai cardiac surgeons, whom he lured back to staff an expanding heart centre at the hospital.
Another reason for biotech companies is regulatory: it's much easier to get government approval in Thailand to conduct trials. Once a procedure has undergone clinical trials, private hospitals only require a nod from an internal ethics committee to license the treatment.
'Thailand has regulatory bodies, but it's not as strict as other countries ... In the US, it takes so many years and so many stages,' said Dr Suphachai Chaithirapan, chairman of Chao Phya Hospital, which also offers TheraVitae's stem-cell therapy.
TheraVitae officials say their next step is to tackle other conditions using blood stem cells. One study under way in Bangkok is treating patients with peripheral vascular disease, which affects blood circulation and can lead to amputations. Further down the line, the technology may offer hope to sufferers of Parkinson's disease, emphysema and diabetes.
But simply treating cardiac patients is already proving a profitable business. By next month, TheraVitae plans to start treating 50 patients a month in Thailand and Singapore, which recently began offering the treatment at two hospitals. The cost of treatment starts at US$34,500 (HK$268,962), excluding travel and accommodation.
Since its founding in 2003, the company had invested around US$5 million and was already making a profit as it continued to grow, said Narin Apichairuk, president of TheraVitae Thailand. It plans to launch an IPO in Thailand in 2008, although it hasn't set a target for raising equity.
As well as expanding to Singapore, TheraVitae is building a laboratory in Thailand to process cells. Blood taken from patients is currently flown to Israel where scientists isolate and multiple the stem cells. The Israeli facility will continue to conduct research and development after the Thai lab opens.
Mr Narin said competition in the biotech industry should eventually drive down the cost of this and other treatments, bringing an experimental technology into the mainstream. 'We don't want to market this as a therapy for the rich. We want it to be the right of everyone to demand stem cells,' he said.
For now, though, much of the demand is coming from ageing Americans who can pay out of pocket for what they see as a last chance at outliving the worst predictions of their cardiologists.
'I figured I had nothing to lose,' said Calvin Miller, a retired firefighter from New Jersey who came to Thailand on vacation after suffering multiple heart attacks and was treated at Siriraj Hospital in Bangkok in 2004, becoming TheraVitae's first paying customer.
Mr Miller, now 57, has since undergone a second stem-cell procedure and lives most of the year in Thailand, where he's taken up a new hobby: scuba diving. 'I'd much rather be in Thailand,' he said.
Cardiologists estimate that about 100,000 Americans suffer heart failure annually, adding to the waiting list for transplants, which are in short supply. Since conventional treatments, such as angioplasty and bypass operations, can't be repeated indefinitely, many eventually become what health officials categorise as 'no-option' cardiac patients.
'There are no cures for coronary heart disease, angina or heart failure. Not are there any on the horizon. All cardiologists are able to do today is relieve the symptoms with certain procedures and drugs,' said Donald Margolis, co-founder of TheraVitae.
But despite the promising early results, stem-cell therapy for cardiac patients and other conditions is still an experimental field. While there's agreement among scientists that adult stem cells may help to regenerate damaged cells, pinpointing exactly how that happens is contentious.
Thai surgeons admit that they can't accurately predict how the stem cells will behave after being introduced into the patient's heart or arteries. Mr Margolis, an actuary, said one in four patients experienced little or no benefit from the surgery. But doctors say it's still a valid response to a terminal medical condition.
'We're not 100 per cent sure [how it works]. We think it's worth a try because we're seeing more and more patients who have no other options,' said Dr Suphachai.
Still, the fact that companies are selling an unproven service to desperate heart patients has raised eyebrows among US researchers in the field.
As chief cardiologist at the Texas Heart Institute in Houston, Dr James Willerson led studies of stem-cell treatments in the US and Brazil, where some of the earliest human trials were conducted in 2000-02. He's also conducted research using human stem cells in mice, including simulating heart attacks to monitor how stem cells fuse with damaged tissue.
Dr Willerson recently began a clinical trial at the Texas Heart Institute with approval from the Federal Drug Administration on cardiac patients using bone-marrow stem cells. He hopes this and other trials under way in the US will eventually pave the way for FDA approval for adult stem-cell treatments, possibly within three or four years. But he has his doubts about commercial therapies being offered in less regulated jurisdictions. 'I feel very strongly that it's premature to offer this kind of thing to people without studies that are carefully controlled, randomised and blind-tested so we can learn what the best cells are, how to give them, and what the risks are,' he said.
Those risks doesn't seem to bother American patients who travel to Thailand for what they see as a final roll of the dice in a game stacked against them. If their luck holds, and their ticker keeps ticking a while longer, they say it's money well spent.
'I feel like I'm at the cutting edge of medicine. I don't feel like a guinea pig. I feel like it's working. That's why I came,' said Mr Stuart.
Mr Narin says TheraVitae informs its patients of the risks of surgery and explains that the technology is still being refined. He admits that the company lacks any long-term data on how stem cells behave in patients' bodies, since the procedure is so novel. But that isn't a reason to stop.
'We don't know exactly what will happen in five years. But we do know we're improving the quality of life for the patients. They don't have five years to wait,' he said.