Karen A. Knudsen

June 30, 1943July 23, 2021

Karen Ann Knudsen, age 78, of Newtown Square, PA, passed away on July 23, 2021 at White Horse Village where she had lived since 2013. Previously she lived in the Upper Roxborough section of Philadelphia for over 25 years.

Born June 30, 1943 in Harrisburg, PA, she was daughter to the late Clarence and Ruth Knudsen. Karen was a graduate of Camp Hill High School. She had a BS from University of Delaware, a MS from Cornell University and a PhD from University of Pennsylvania. She was retired from Lankenau Institute for Medical Research where she worked for 25 years as a research scientist. As stated by a friend and colleague: “Dr. Knudsen was a meticulous and imaginative scientist who made ground-breaking contributions to our understanding of the importance of cells adhering to one another in particular ways for normal embryonic development and tissue function, and how disruption of these adhesions may lead to diseases such as cancer. Karen was a treasured colleague, mentor, and friend.” Karen was a pioneer for women in science and a strong advocate for equal rights. She served as president for the Philadelphia chapter of NOW in the1970s. She loved being outdoors whether it was a stroll through the woods, camping with friends or a multi-day backpacking trip in Alaska. Every place she lived, she had some form of a garden. She thoroughly enjoyed working hard to make a patch of land beautiful or fruitful. Reading was one of her many passions. She read voraciously, enjoying books across a wide range of genres – from in-depth scientific publications to Pulitzer Prize winners to novels of first-time fiction writers. Family was of the utmost importance to Karen. Some of her happiest times were those when she was at the shore with her brothers and their families and later with her grandsons. She retired the day her first grandson was born. She was a working mother, but pledged not to be a working grandmother! She spent many hours caring for, playing with and teaching her two grandsons. They have fond memories of learning how to fist fight from their grandmother (she had grown up with three brothers). Surviving are her loving daughter Carla Hetzel; a son-in-law, Joel Neigh; two grandsons Acheson Neigh and Gregor Neigh; two brothers, Paul Knudsen and David Knudsen; two sisters-in-laws, Charlotte Knudsen and Jan Knudsen; 6 nieces and 1 nephew and 9 grand nieces and nephews.

We will hold an informal picnic memorial to gather and share memories of this strong, unique woman and her husband Charles Hetzel who died July 1, 2020. The memorial will be August 19, 2021 at Ridley Creek State Park Pavilion 11-A and 11-B (flexible timing 10-2pm).

Contributions in Karen’s name can be made to the Parkinson’s Council: 12 W. Willow Grove Avenue Philadelphia, PA 19118 Or Planned Parenthood:


No public services are scheduled at this time. Receive a notification when services are updated.


Karen A. Knudsen

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Mindy George-Weinstein

August 11, 2021

I first met Karen many years ago when she was transitioning from Rick Horwitz's lab at Penn to a postdoctoral fellowship with Clayton Buck at the Wistar Institute. I was immediately impressed with her intelligence and warmth. Our friendship grew in parallel with our professional relationship. Karen was a thoughtful scientist and respectful colleague who taught me how to write compelling grant applications and impactful manuscripts. Although a legend in the field of cadherins, she was extremely modest and never missed an opportunity to speak highly of the work of others. She had an unusual ability to balance her professional responsibilities with other aspects of her life that were most dear- her family, friends and natural surroundings. I can still envision her clear, wise eyes as she pondered the meaning of experimental data and the joy that accompanied her laughter.

Susan Gilmour

August 3, 2021

I too loved Karen. She was not only my friend but also a role model for me as I started my own lab at the Lankenau Institute for Medical Research. Karen was a brilliant and innovative scientist who was generous with her time and ideas, making her the ideal colleague and collaborator. I loved how she balanced her deep love for her family and her career with so many other interests including gardening and her voracious appetite for reading. Although Karen could (but never did) boast of many accomplishments (biology of cadherins and adhesion proteins and her many leadership roles including as a principal investigator and scientific director of the institute), I believe that Karen was most proud of her daughter Carla and her two grandsons. Karen was a champion for women, and so many of us women in science owe her so much for her support and kindness at all the right moments.

Rick Horwitz

July 27, 2021

I am so saddened to hear about Karen's passing. She was my first graduate student at Penn. As she began graduate school relatively late, we were nearly the same age and bonded immediately. I recall her happiness when she found her husband and had her daughter - they were the loves of her life!

Karen was a natural scientist, possessing an amazing technical expertise and intellectual authority beginning the day she started in my lab. She was also a wonderful, caring and sharing person. Everyone not only respected Karen, they also loved her, as she helped everyone become better scientists and people.

Karen's research with me set the stage for major discoveries that lie just up the road for my lab, for her postdoc, and in her independent career. In this way, she was an extraordinary student.

While she will be greatly missed, our lives and memories are enriched by the time we all were able to spend with her.

Rick Horwitz

Christa Smolenski

July 26, 2021

I worked for Karen for six years. I have so many fond memories and moments. She hired me right out of college (2000) and I knew the moment I walked in her lab, it was the place I was meant to be. She was my boss, but she was also a colleague and a friend. She helped shape me into the person I am today during those six years I spent in her lab. I think of her often and she will remain a presence and influence throughout my life. When I’m enjoying nature…particularly the birds and the snow, I often think of her. You will be missed, Karen. Rest In Peace.

Loretta Rossino

July 26, 2021

I loved Karen. She was a sweet, kind, giving, loving and wonderful woman who was my supervisor at Lankenau Institute for Medical Research. What I saw in Karen was her generosity. During lunch at work, we would take walks and she shared her knowledge of nature and plants. I learned much. I also got to know her daughter and grandson. She loved her sisters in law, Janet and Char and spoke of them often.

While we were still working, I was planning a flower bed and Karen would bring rocks from the fields in her back yard for me to use in my garden. Til this day, I look at the beautiful rocks and they remind me of Karen. Rest in peace Karen. You will be missed.