• Rotator cuff tear has a high re-tear rate after rotator cuff repair surgery.
• Stem cell therapy is gaining attention for promoting tendon healing.
• Patients should consult with orthopedic surgeons before deciding on treatment.

Cartilage or tendon could be damaged due to aging process or unexpected accidents.

These are essential tissues directly related to body movement, but once damaged, they cannot recover or regenerate themselves. So, after the injury, the quality of life decreases significantly.

However, regenerative treatment using autologous stem cells are thought to be able to recover those tissues and it can improve the quality of life.

I interviewed Joo Han Oh, a professor of Orthopaedic surgery at Seoul National University Bundang Hospital, for detail.

- Autologous stem cells are a relatively unfamiliar concept. Please explain the concept with details.

Stem cells refer to immature cells in the primitive stage that can differentiate into various cells.

The main characteristics include self-renewal and differentiation ability.

It is emerging as a new hope for joint diseases because under specific environment and conditions, it can be differentiated into various cells, such as the cells of bone and muscle.

Autologous stem cells indicate stem cells extracted from the patients’ body.

It can be collected primarily from bone marrow, fat, synovial membrane, and blood.

It was mainly collected from bone marrow in the early days, but it has expanded to fat cells, synovial membranes, and blood.

- Among various types of stem cells, which of these are used for autologous stem cell therapy?

There is various type of stem cells, such as embryonic stem cells, adult stem cells, and induced pluripotent stem cells.

Stem cells currently used in autologous stem cell therapy are adult stem cells (stem cells which present in adult blood, fat tissue, bone marrow, nerve, muscle, skin, cord blood, etc.).

Recently, mesenchymal stem cells (one of adult stem cells which present in cartilage, bone, fat, bone marrow, etc.) are gaining attention.

Stem cell therapy uses stem cells whose properties have been identified after primary culture.

For example, bone marrow stem cells indicate cultured stem cells of the buffy coat layer formed by centrifuging bone marrow aspirate.

On the other hand, adipose stem cells refer to the cells obtained by monolayer culture of the lower interstitial compartment layer formed after centrifugion. Centrifugion is done after decomposing connective tissues from lipoaspirate with enzymes.

Thus, transplanting bone marrow aspiration concentrate or fatty interstitial compartment concentrate itself should not be referred as stem cell therapy, strictly.

- Which diseases are autologous stem cells currently being used for?

With the recent emergence of regenerative medicine, stem cells have drawn attention as one of the treatment methods to restore the functions of damaged and degenerated cells and tissues.

Since then, numerus studies regarding stem cells have been conducted in the field of orthopedic surgery concerning tissue regeneration of tissues such as bone, cartilage, tendon, and ligament.

In Korea, stem cell therapy has begun to be actively applied for patients after passing the final review on safety and effectiveness in December 2011 from the New Medical Technology Evaluation Committee of the Ministry of Health and Welfare.

Initially, it was widely used as a treatment for cartilage regeneration in osteoarthritis of the knee joint. Now, it is currently used to treat various tissues of the musculoskeletal system, such as tendon regeneration in rotator cuff tears and bone regeneration in fracture patients with extensive bone defects.

- How different is the outcome of stem cell thearpy compared to previous treatments?

I am specialized in sports medicine and the shoulder joint in the department of orthopaedic surgery.

And I have been researching the treatment of rotator cuff tear, the most common degenerative disease in the shoulder joint.

Once the rotator cuff is torn, the primary treatment is to repair it surgically. However, when the tear is chronic and large, it has a high re-tear rate.

Accordingly, technical methods and suturing devices have been continuously developed to strengthen the suture to reduce the re-tear rate.

However, it could not significantly decrease the re-tear rate, and tears with the size of more than 2 cm showed 20% to 94% of re-tear rates.

Therefore, regenerative therapy, which can promote bone-to-tendon healing, are gaining attention recently.

Various studies are in progress to promote tendon healing by appling stem cells to the repaired site after rotator cuff repair.

In 2013, we reported a study that adipose-derived stem cells could help improve fatty degeneration and rotator cuff healing in a rabbit model and we received the Charles S. Neer Award, the most honorable academic award in the field of shoulder joint, from the American Academy of Orthopedic Surgery and the American Shoulder and Elbow Society. Clinical trial using stem cells derived from autologous fibroblasts is also in progress.

Regarding osteoarthritis of knee joint, there has been no effective treatment for slowing down the progression of the disease or restoring damaged cartilage in osteoarthritis of grade 2 to 3. (Osteoarthritis is classified into Kellegren-Lawrence grade 1 to 4 depending on the degree of cartilage damage).

However, after the introduction of regenerative treatment, stem cell therapies for regenerating cartilage have been tried and being used. Currently, various autologous stem cells, including autologous bone marrow concentrate, are used for the treatment.

- Are there any patient groups who are difficult to apply autologous stem cell therapy?

Autologous stem cells come from patients themselves, therefore risk for immune reactions, which is relatively common in current stem cell therapy, is low.

However, it is not applicable for all musculoskeletal diseases.

Although indications are expanding, stem cell therapy is not yet standardized for all diseases. Patients need to consult an orthopaedic surgeon to see if they can expect good clinical outcome through the stem cell therapy.

In osteoarthritis of knee joint, the degree of damaged cartilage and patients’ age affects the outcome after the treatment.

In end-stage arthritis with extensive cartilage damage, the success rate of autologous stem cell therapy is low. As aging progresses, stem cell activity decreases, making it challenging to collect the potent stem cells.

In Korea, stem cell therapy using autologous bone marrow concentration is restricted to those aged 15 to 50.

- You are currently participating in a national project of developing domestic medical devices organized by the Korea Health Industry Development Institute.

Recently our team was selected as a partner for this project, and I am conducting clinical trial to determine the effect of autologous bone marrow concentrate in rotator cuff tears.

Bone marrow concentrate contains pluripotent stem cells which are known to be able to differentiate into bone, cartilage, and tendon.

Also, it would help restore the original anatomy of bone-to-tendon interface as it contains various growth factors.

Therefore, I have decided to use the concentrated bone marrow stem cell using Tricell BMC PRO kit of Rev-Med, considering that it is ideal for collecting and concentrating stem cells rich in growth factors without contamination.

Also, an appropriate medium is needed to activate and maintain the regenerative potential of the bone marrow concentrate.

Therefore, we selected an atelocollagen made of Type I collagen extracted from swine as a transport medium, because it is one of major component of tendon tissue and it could cover the damaged tissues by integrating into adjacent tissues.

So, I intended to evaluate the radiologic and clinical outcomes after injecting the bone marrow concentrate and the transport medium into the repair site after rotator cuff repair.

- Please explain more about future research plans for autologous stem cell therapy.

I am researching not only the stem cell itself, but also the effective transport mediums for the effective delivery and activation of stem cells with various institutions such as Columbia University.

Furthermore, by utilizing technologies such as 3D printing, I am attempting to develop a medium that can effectively deliver specific factors to the injured lesions.

I am expecting favorable results from the current animal trial, and I will report the outcome after analyzing the data.