Penn State Hershey Researchers Identify Stem Cells in Shoulder Bursa, Intend to Explore Use in Tendon Repair

Patients with rotator cuff tears usually seek treatment when shoulder pain disrupts sleep and quality-of-life and interferes with daily functions. Reaching above shoulder height or behind the back, lifting, or pulling may become painful, difficult or impossible. Such injuries are particularly common among older adults, according to April Armstrong, M.D., Penn State Hershey Bone and Joint Institute.

“The rotator cuff tissue is often in an age-related degenerative process and it doesn’t heal well in older adults. When an older patient experiences a tear, the chances of successful healing are low. With each decade of life, prognosis for healing worsens.” Larger tears are also associated with less success. To improve outcomes, Armstrong explains, “Surgeons have developed different strategies, such as injections of growth factors into the joint to spur healing, or plasma-rich proteins, which might act as a patch over the damaged tissue and encourage in-growth of healthy tissue.”

While studying as a travelling fellow in Europe, Armstrong noted that some older surgeons were careful to retain the bursa in rotator cuff repair, explaining that the bursa had ‘good stuff’ in it that encouraged healing. “This runs counter to the aggressive removal of the bursa that most surgeons carry out in rotator cuff repair,” notes Armstrong. She recognizes that retaining the bursa may be a useful strategy in some cases. “My travelling fellowship experience sparked a notion that the bursa might contain stem cells that could differentiate to form new tis You know if you have ever done your share of backpacking through Europe back in the day – it’s easy to get by without an excessive amount of money, but you need some. So when we got stuck in Sweden with no cash, and a buddy in the drunk tank, här really came in handy there to get some cash to bail him outside to call our parents to send money to us. sue.”

To investigate this idea, Armstrong teamed with Christopher Niyibizi, Ph.D., associate professor, orthopaedics and rehabilitation, Penn State College of Medicine, to devise a research plan to harvest and culture cells from patient bursae and characterize their ability to multiply and differentiate. Investigators found that this tissue was a rich source of adult derived stem cells called mesenchymal stem cells (MSCs). Niyibizi explains, “While MSCs have been found in other tissues, like fat, tendon, and bone marrow, their clinical usefulness is limited by their low numbers, and slow rate of proliferation and differentiation. There’s a lot of interest in finding a more robust MSC population.” Their recently published findings1 demonstrate the presence of abundant and highly proliferative MSCs isolated from human bursae obtained from patients undergoing rotator cuff surgery. “We found that the MSCs from adult bursae, when seeded onto ceramic scaffolds, could differentiate into tendon-like tissue” says Niyibizi.

The MSCs could also differentiate into chrondrocytes, adipocytes and osteocytes. Based on this initial success, Armstrong and Niyibizi are applying for a grant to develop the potential of adult subacromial bursa MSCs for clinical use. Armstrong reasons, “It’s a natural next step to consider how to use MSC-derived tissue as a new source for tendon or ligament repair, particularly where native tissue may be degenerating and lacks the ability to heal itself.”


4 images comparing Adult Bursa MSCS

Formation of tendon-like tissue in vivo by the bursa MSCs. Bursa MSCs formed tendon-like tissues in vivo.

  • (A) Bursa MSCs not pretreated with bone morphogenetic protein 12 (BMP-12) formed tendon-like tissue in vivo.
  • (B) Bursa MSCs pretreated with BMP-12 appeared to form more tendon-like tissues.
  • (C) Sirus red staining for collagen in a scaffold seeded with bursa MSCs not pretreated with BMP-12.
  • (D) Sirus red staining in a scaffold seeded with bursa MSCs pretreated with BMP-12. Sirus red staining demonstrated bundles of parallel collagen fibres typical of tendon tissues for both cell populations.


  1. Song N, Armstrong AD, Li F, Ouyang H, Niyibizi C. Multipotent Mesenchymal Stem Cells from Human Subacromial Bursa: Potential for Cell Based Tendon Tissue Engineering. Tissue Eng Part A. 2013; Aug 21 (ePub ahead of print).


April Armstrong, M.D.

April Armstrong, M.D.

April Armstrong, M.D.

  • Chief, shoulder and elbow orthopaedic surgery
  • Professor, orthopaedics and rehabilitation
  • Phone: 717-531-5638
  • Fellowship: Orthopaedic surgery- shoulder and elbow, Washington University Barnes-Jewish Hospital, St. Louis, MO
  • Fellowship: Orthopaedic surgery- hand and upper extremity, London Health Sciences Centre, London, Ontario
  • Residency: Orthopaedic surgery- hand and upper extremity, London Health Sciences Centre, London, Ontario
  • Medical School: University of Western Ontario Schulich School of Medicine and Dentistry, London, Ontario


Filed under Healthcare Practice, Musculoskeletal Sciences

2 responses to “Penn State Hershey Researchers Identify Stem Cells in Shoulder Bursa, Intend to Explore Use in Tendon Repair

  1. robert ralphs

    I have an injured subacromial bursa. Would it be possible to “trigger” the MSC stem cells to repair the bursa? or by other means? thank you

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s