July 5, 1996
Page 2 of 3
Seegmiller was in internist whose primary interest was in diseases where crystals appear in body tissues. He felt these crystals would provide a biochemical "handle" to understanding the disease process. His main interest was in gout and realted disorders of purine metabolism. In gout, urate crystals accumulate in kidney and other tissues secondary to high urate concentrations in body fluids -- that is, they "precipitate" in the tissues. Bickel and his group had thought -- although Dent did not -- that cystinotic crystal deposition might occur in the same way.However, by 1968, Seegmiller, Schneider, Crawhall and others -- including the very talented technologist Kathryn Bradley -- had shown unequivocally with quantitative techniques that cystine & cysteine (reduced cystine) levels were normal in cystinosis plasma.
Seegmiller and Schneider, and subsequently I and still later Bill Gahl, were able to use the resources of the NIH to develop a large following of cystinosis patients to participate in research and clinical trials. In these early days especially, it was easy to get the funds to travel patients to the NIH and when necessary, to investigate them there for long periods. Indeed, one large family with several cystinotic children was resettled from West Virginia to the Washington, D.C. area for research as well as for compassionate purposes.
In 1968, Schneider and Seegmiller made some crucial observations. Cystine levels were found to be greatly increased in white cells and cultured fibroblasts from cystinotics. A smaller increase was found in these cells in obligate carriers. So the intracellular increase was found as a primary phenomenon in vivo and in vitro . They also observed that if these cells were gently broken, the cystine did not remain in solution but centrifuged down with a mixture of subcellular particles. This led to the crucial hypothesis of "subcellular compartmentalizaiton of cystine." But the questions still remained -- where in the cell was the cystine and how did it acumulate there? And, of course, if we understood this, how could we then get the cystine out as it was felt to be harmful to the cells?
In 1968, I joined Seegmiller's lab and Dr. Schneider had moved to another NIH research team. We became close friends during the years from 1968-1970 when he moved to start his own cystinosis laboratory in San Diego. Our scientific collaboration continued for many years thereafter and our friendship has continued to the present time. Jerry and I had innumerable discussions about cystinosis in those days and were constantly exchaning ideas.
It seemed crucial to ask, "Where in the cell was the cystine?", and this became the main focus of my research at that time. Some investigators believed the cystine was in the energy centers of the cell, the mitochondria, while others such as Des Patrick and the electron microscopist Brian Lake working at London's Children's Hospital had some photographs suggesting that cystine crystals were inside lysosomes -- the membrane enclosed sacs within cells that were thought to break down large molecules into small ones.
We were able to show convincingly that the cystine was, in fact, in lysosomes even when it was not in crystalline form -- that is to say, the cystine accumulated and later could crystallize in lysosomes, ultimately killing the cells. We also found that a cystine-like compound, cysteine-penicillamine disulfide, could be made to selectively accumulate within the lysosomes of cystinotic fibroblasts in culture.
Meanwhile, we carried out with Frank Tietze an extensive series of studies of the ability of cystinotic cells to reduce cystine to its soluble half-form, cysteine. Like Patrick's studies, all these investigations were normal, and where possible we had found this to be true at the subcellular level as well. We still couldn't tell why the cystine was accumulating, or what to do about it.
At this time, possible treatments of cystinosis were also being developed. Bickel and his group studied for years the possibility that a low cystine diet would retard the progress of cystinosis; they had many collaborators on this work mostly from European teams, and reported their results in the book on cystinosis that I edited in 1972. The results were extremely disappointing after years of effort and sacrifice on the part of patients and their physicians.
Therapy with various drugs was also tried in several centers, again with initial promise but ultimate failure. Therapeutic attempts involved drugs thought able to interact with (reduce or solubilize) cystine such as dimercaprol (BAL), penicillamine, and dithiothreitol (DDT). None of them worked.
However, it was recognized by Schneider and others that additional related compounds could be and should be tested -- and this later became a major research theme in Jerry's laboratory in San Diego.
The demonstration that cystine was an intracellular storage problem in cystinosis opened the door to developing the first effective treatment for this disease -- namely, renal transplantation. This treatment has saved many lives. It was through the experiences of post-transplant cystinotics, however, that we came to realize the limitations of this treatment which are secondary to the continued accumulations of cystine in other tissues and their eventual damage.