Clemens Fritsche

Home Institution
Humboldt-Universität Berlin

Host Institution
Tissue Engineering and Organ Fabrication Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, MA
Research Mentor: Joseph P. Vacanti, M.D. John Homans Professor of Surgery at Harvard Medical School and Director of Pediatric Transplantation at Massachusetts General Hospital

E-Mail: clemens_fritsche@yahoo.com

Research Topic
see Abstract
Personal Reactions to the U.S. Experience
"If there is only one place in the world where you can realize your scientific ideas, that place would be here," my professor told me one day. I really was amazed by all the opportunities in Mass Bay and had to be careful not to try to get involved into too many different projects! Research at such a straightforward and professional level was something I had not experienced before! The friendly and respectful way even renowned professors like E. Braunwald and others, but above all, J. Vacanti, treated me, a foreign student, encouraged me to work even more and not to give up after some screwed-up experiments. On the other hand, all that led to sometimes a 60-hour week (no kidding!) in the laboratory.
Even if I don't agree with what some Americans do and the way they might see themselves, I feel as though I gained some insight into how they think and feel. This made me understand some things that stuck me when I first came to the U.S. You don't have to betray your ideals to get along with the American way!
Greatest Difficulties Encountered
Having been prepared that housing in Boston is a very big issue, I was lucky to finally find a decent furnished room in a very nice apartment not too far from everything (25 min. by bike or 20 min. by the T to Charles Street). Since the BMEP Academic Year usually starts at about the same time as all American students return to school, you have to be either very rich or very lucky not to finally end up moving into a room that wouldn't even be used as a closet back home in Germany!
As no one could really tell us how much money one would need for these months in the U.S., I expected the worst, and I must confess that, at least in Boston, life can really be more than twice as expensive as in Berlin. When I sometimes paid $7 for a beer, plus tip, I felt that I was being robbed. But even when paying a fortune to replace my stolen bike (Hey punks, one day I'll get ya!), one gets used to this expensive life.
I don't want to turn this into a political statement, but perhaps I should mention that while living here I sometimes had some fundamental disagreements with the American government concerning their foreign policy, which led to some fierce discussions with American friends and roommates - mostly hopeless and depressing!
Most humorous incident
Never confuse "germ" and "sperm", as I did on a hygiene certification class for my laboratory - they are still laughing about me!
Helpful Hints for Future Students
- Think big - do bigger.
- Get your visa early.
- For a place to stay check out craigslist.org or bostonapartment.com even earlier.
- If you have a bank account at the Deutsche Bank, when you withdraw cash with your EC card at the ATM at the Loews Cinema (Tremont Street) you won't be charged any extra fee (cooperation with the Bank of America).
- Use the Chinabus when going to New York - fair prices, funny people, decent ride!

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Abstract on Research Topic
Early Approaches in Tissue Engineering of the Lung
Authors
Fritsche CS (1), Simsch O (1), Shin M (1), Kaazempur-Mofrad M (2), Borenstein J (3), Vacanti JP (1)
Institutions
(1) Tissue Engineering and Organ Fabrication Laboratory, Massachusetts General Hospital, Harvard Medical School
(2) Massachusetts Institute of Technology
(3) Draper Laboratory Inc.
Background
Tissue Engineering represents a new and promising concept to create functional and viable tissues and organs from autologous cells. Great advances in tissue engineering of many tissues and organs have been made over the last years, but very few efforts have concentrated on developing living and functional lung tissue. The need of metabolic and oxygen supply still limits the feasibility of creating large three-dimensional structures and complex parenchymal organs like the liver, heart, kidney and lung.
Methods
In this experimental setting we are seeding MLE-12 cells (ATCC, Manassas, VA), which is a transgenic mouse cell line, that has previously been used as a model for human type II alveolar cells, into a functional unit, consisting of a parenchymal compartment and the correspondent vascular compartment. These units (designed in cooperation with the MIT and the Draper Laboratory, Inc.) are made of biocompatible Polycarbonate (PC) and Polydimethyl-siloxane (PDMS) by silicon microfabrication and provide a microvascular network, that can supply the construct with nutrients and oxygen at a defined level of flow and pressure. The cells have been transfected with a murine GFP-virus in our laboratory and subsequently purified by FACS to visualize their proliferation and growth in the parenchymal compartment over time by fluorescence microscopy. After the cells have been maintained in culture for up to two weeks the constructs are evaluated by histology, live/dead staining, immunofluorescent staining for SP-C (surfactant associated protein C) and the Hoechst-DNA assay. Further morphologic and functional evaluation is planned. Subsequently, co-culture of MLE-12 cells with endothelial cells by seeding HMEC (human microvascular endothelial cells) into the microvascular network of the devices is also being done and evaluated with immunofluorescence.
Preliminary results
The MLE-12 cells stain positive for SP-C and survive culture on the used polymers for the experimental period. They can be maintained in culture in the parenchymal compartment of the microfabricated devices. The HMECs can be cultured in the microvascular network, as previously shown by other experiments in our laboratory.
Current efforts are being made to improve the culture conditions in the devices. Further and more detailed results of all the experiments can be submitted by the end of this academic year.

Conclusion
This new approach evaluates the feasibility of controlled development of living and functional respiratory tissue. This preliminary data might be applicable to extracorporal assist-devices for reoxygenizing liquids for use in intensive care medicine. It might also reveal new opportunities for experimental testing of pharmaceutical uptake over the respiratory membrane, which could be performed on this living in-vitro model of the lung.