Experimental Histology 19491951

After my first year at the Karolinska Institute, I was asked by Professor Hjalmar Holmgren to be an unpaid instructor of histology. This was a common way at the time to recruit graduate students. Hjalmar Holmgren held a personal chair of experimental histology. His main contribution had been the identification of heparin in mast cells, but he was also very interested in the regulation of the daily rhythm as mirrored in the biochemical processes in the liver. He was a young energetic man, coming from a well-known academic family, and he had a great sense of humor.

Hjalmar Holmgren surrounded himself with a group of very active researchers. Two associates were Hungarian and one of them, Endre Balazs became my teacher. His nickname used by everybody is Bandi. Balazs had escaped from Hungary in 1947 before the communists took over. His main interest was connective tissue and the interplay between fibroblasts and extracellular matrix and he was especially interested in the mucopolysaccharide hyaluronic acid (later renamed glycosami-noglycan and hyaluronan, respectively).

We were two young students engaged by Balazs, Jan von Euler and myself. Jan, who was a son of Hans von Euler and a brother of Ulf von Euler (both Nobel laureates), was a highly intelligent boy and very much appreciated by everybody. He was put on a project to determine the presence of hyaluronidases in serum of cancer patients, but I do not think that any results came out of it at that time. Jan - still young - succumbed to depression, which shocked us all.

I myself was asked to prepare hyaluronan from umbilical cords. Balazs wanted to test its effect on cell growth in tissue culture. In order to obtain fresh umbilical cords, I had to bribe the midwives at the Karolinska Hospital with cakes. Then I followed well-published procedures to prepare the polysaccharide, which included extraction with a salt solution, removal of proteins by shaking with chloroform and isoamyl alcohol (Sewag technique), and repeated precipitations with ethanol. When the polysaccharide was sufficiently pure it had to be sterilized. Due to the high viscosity of the solutions, we could not use ultrafiltration and finally we had to autoclave them.

Tissue culture at this time had to be performed under strictly sterile conditions as we had no antibiotics. Small pieces of chicken hearts were placed in a hanging drop of fibrin, and the migration of fibroblasts out of the tissue was followed microscopically. The microscopic picture was enlarged and the area that was covered by cells was measured by planimetry.

During this work we made several interesting observations. In the extraction of hyaluronan from the umbilical cords at different salt concentrations and at varying pH, I found highly different viscosities of the extracts and thought that the extraction procedures were not equally effective. However, it turned out that the viscosity of hyaluronan was highly dependent on pH and ionic strength. Today, this is trivial but at that time it had only been shown for some synthetic polymers by Raymond Fuoss. The observation resulted in a publication in Journal of Polymer Science: "Viscosity function of hyaluronic acid as a polyelectrolyte.'' In our search for techniques to sterilize hyalur-onan, we also used ultraviolet irradiation. To our surprise the viscosity disappeared. Later it was also shown that irradiation with electrons degraded hyaluronan. What we had observed was probably the first example of free radical degradation of hyaluronan. Finally, we could show that hyaluronan promoted fibroblast growth while sulphated polysaccharides were inhibitory. This was the first example of how cellular functions can be regulated via an interaction with hyaluronan. In the resulting publication we also showed that heparin could not be a sulphated hyaluronan and we also, probably for the first time, described biological effects of heparan sulphate [1]. As a side line, I also published a paper on the effect of ultraviolet irradiation of glucose.

My initial collaboration with Bandi Balazs lasted for one and a half years. When the Korean war broke out he decided to move to Boston, where he was employed by an ophthalmic surgeon, Charles Schepens, to do research on the eye at a laboratory named Retina Foundation. In a very short time, Bandi developed this laboratory into a major eye research institute.

Endre Balazs has continued to be an important person in my life and it is appropriate at this stage to tell the reader why he always has fascinated me. It is only a ten-year age difference between us but with time we almost developed a father-son relationship. The characteristics of Bandi could be summarized in the words: warmth and generosity, scientific imagination, hard working, unyielding, and entrepreneurial. He has always had numerous ideas, has never been afraid of starting large-scale projects, has been able to convince granting agencies and others to finance them, and his success rate has been high. It is not surprising that I found it stimulating to work with him but then - in the end - I realized that we had to go separate paths if I should be able to carry out my own ideas.

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