Timothy Brown made medical history when he became the first patient who was essentially cured of HIV, after receiving a stem cell transplant from a person who was genetically resistant to the infection.  Now, doctors are hoping to build on Brown’s success by treating HIV patients using cord blood units that have the same HIV-resistant gene.Brown, 46, was a student living in Berlin in 1995 when he tested positive for HIV.  He responded well to therapies for the disease until 2006, when doctors also diagnosed him with acute myeloid leukemia.  The doctor who treated Brown, Dr. Gero Hütter from Berlin’s University Hospital, proposed to tackle his leukemia by using chemotherapy to wipe out his immune system, and then rebuild the immune system with a bone marrow transplant.However, when searching for an appropriate match, Hütter kept his eyes out for a specific donor: one who carried a genetic mutation called delta 32, which disables the CCR5 receptor on immune system cells.  The CCR5 receptor is the one HIV uses to infect its victims – meaning people who carry the mutation are essentially immune to the disease.  Approximately one percent of Europeans carry the mutation, but it is rarer people of African, Asian, or South American descent.Out of 232 potential donors, Hütter found a match for Brown, who also carried the delta 32 mutation, on the 67th try.  The doctors performed the transplant, repopulating Brown’s bone marrow cells with the donor cells.  Months later, Brown was in remission for leukemia and had no trace of HIV in his body.  And while Brown’s leukemia eventually recurred a year later, necessitating another transplant, his HIV never did.  "I still have some disabilities due to the treatments – it’s not perfect,” Brown told FoxNews.com, explaining that he suffered from speech and balance issues following the procedure.  "But it is my life, and I’m very happy not to have to worry about HIV anymore.”However, Brown’s stem cell transplant isn’t feasible as a widespread treatment for HIV patients, according to doctors.  It can be highly difficult to find a matching bone marrow donor – let alone one who also carries the HIV-resistant gene."The cord blood idea came about later because of the success with my transplant,” Brown said.  "…In my case, using stem cells, they had to find a perfect match for me.  With cord blood, you don’t have to use donors that are  an exact match, so it means doctors are more likely to find a donor who will work.”Dr. Lawrence Petz, a stem cell transplantation specialist, as well as chief medical officer for StemCyte and president of the Cord Blood Forum, explained cord blood essentially gives doctors more leeway in regards to matching patients with donors and opens the possibility of treating many more people."At the present time, I feel there’s no other way to cure a reasonable number of patients other than using cord blood,” Petz said.  Two weeks ago, a patient in the Netherlands was the first to undergo this potentially revolutionary treatment.  As was the case with Brown, the transplant was primarily done to address another disease, but doctors specifically selected a unit of cord blood that contained the HIV-resistant gene in hopes of curing that as well.   Another similar surgery is scheduled for a patient in Madrid within the month."We don’t know the final outcome yet, but we’re very optimistic that the transplant will be of significant benefit to the patient,” Petz said.  "Usually it takes some months after the procedure to determine the outcome [while the recipient’s cells are being repopulated with the donor cells], so we’re keeping an eye on it very closely because it could be of historic interest.”Petz explained that as of now, the treatment isn’t meant for all HIV patients.  The inventory of cord blood units that carry the HIV-resistant gene – 100 out of 17,000 tested so far – needs to be built up over time.  Petz said he believes HIV patients with other hemolytic disorders, such as Brown and the Netherlands patient, and AIDS patients who do not respond well to current drugs on the market, should be considered for the transplants.