The Anabolic Era of Orthopaedics: Stem Cells - which ones to use?

Orthopaedic Tissues transplanted into humans are dead.

That’s right: Other than hearts, livers and kidneys that must be kept alive for immediate transplantation, any tissue that is removed from a donor or a cadaver, frozen, washed, sterilized and finally delivered to a surgeon is dead. From there it may be used in new ACL grafts, meniscus replacements, rotator cuff patches, tendons for the hands and feet… the list goes on. 

The surgeon relies on the patient’s healing ability to recognize and revive the dead donor graft. The body does this by sending scavenger cells that open up pores for the new blood vessels to bore into, lacing new blood vessels into the tissue, and finally sending specialized cells that lay down new collagen and restore the graft to life.  In ligaments, this wonderful tissue regeneration process is called “ligamentization”; in other tissues, “remodeling.”

But the process of remodeling takes time, and during that period of restoration, the tissue is at its weakest stage.  A new injury doesn’t need to be very forceful to tear the healing tissue.  And any illness might slow down the process.  An early return to sports might put too much stress on the graft, leading to stretching—or, in the worst case, a complete failure to remodel.

But why, in the 21st century, do we rely on nature alone to heal our repaired and replaced tissues?  Fortunately, the entire field of tissue regeneration is changing rapidly—and the Stone Research Foundation is at the forefront of this research.

We are now in what I call the “Anabolic Era” of orthopedics, where we recruit stem cell derived self-repair cells, inject growth factors, and use electrical stimulation and other tools to juice up the healing process.  But stem cell science is advancing so rapidly that we now have off-the-shelf products with the highest desirable concentrations of stem cell recruitment and growth factors for every application. 

Stem cells are pluripotent cells that produce progenitor cells that have a wide range of healing growth factors, along with anti-inflammatory, anti-scarring, and antimicrobial agents. 

Over the last few years, in the Stone Clinic, we concentrated and combined patients’ own growth factors with donor tissues before using them to rebuild ACLs and meniscus tissue. 

Here is a shortlist of the pros and cons of the stem cell  activation sources used today:

Fat:

• Pros: very vascular with many cells
• Cons: Requires a surgical procedure; cell numbers decline with age

Bone:

• Pros: Marrow cells are more similar to cartilage and bone
• Cons: Painful bone marrow biopsy procedure; cell numbers decline with age

PRP:

• Pros: easy access with a needle puncture. Less expensive. Growth factors 2-5x normal
• Cons: Requires a blood draw. Concentrations of platelets vary by time of day and other factors

Today, tissues transplanted in our clinic are pre-loaded with these growth factors. We must now do the basic science to determine the optimal concentrations of these factors when infused into tissues and the clinical science to demonstrate if, and how much faster, the body heals with the use of these tissues—and if effective enough the application of stem cell recruitment and growth factors may quickly become widespread, leading to accelerated tissue repair.