Mesenchymal stem cells yield promising results, multiple orthopaedic applications

Although research on the use of stem cells in orthopaedic surgery is still in its infancy, there are promising early results in cartilage repair, treating nonunions and osteoarthritis. Significant work remains, however, before they can be used routinely in patients.

“The use of stem cells in orthopaedics is quite a recent technique,” Alberto Gobbi, MD, president of Orthopaedic Arthroscopic Surgery International, in Milan, Italy, told Orthopaedics Today Europe. “The application of mesenchymal stem cells (MSCs) in regenerative medicine is quite new.”

Image: Sankineani S

However, the use of these cells in orthopaedic surgery is increasing rapidly, according to Gobbi. “We know that we can help the healing of bone [and that] we can help the healing of tendons and of cartilage” with stem cells, he said.

“Mesenchymal stem cells have had a big impact on orthopaedic surgery over a short period of time,” said Ramon Cugat, MD, PhD, who is president of the medical council for the Catalan Soccer Delegation’s Health Insurance Company under the Spanish Soccer Federation. “This impact continues to grow on a daily basis.

“The big difference between treating with cells and traditional treatments is that cells focus on regeneration,” said Cugat, an Orthopaedics Today Europe Editorial Board member. “Until now, orthopaedic surgery has focused on restoring the anatomy and recovering function. Now it is time to work with biology.”

Cell-based treatments work with biology by inducing regeneration; they restore the tissue with its original properties. With repair, the tissue is restored without conserving its original architecture and function, Cugat said.

With all of this promise comes great excitement; however, orthopaedic surgeons must remember the field is still growing and data are lacking, these experts noted.

“It is a developing field, which I think is associated with a lot of hope and expectation, but I do not think we have much in the way of solid data yet to talk about its clinical contributions at this point,” Thomas A. Einhorn, MD, professor and chairman of the department of orthopaedic surgery at Boston University, in Boston, said.

“Lots of animal studies have been done — many of them with very positive and very encouraging results — but to my knowledge, there has not been much in the peer-reviewed literature on really good clinical studies,” Einhorn said.

Correct terminology needed

In this article, specialists discussed the latest stem cell research. They all agreed that any discussion of this topic must start with the correct terms.

“One thing that I think needs to be pointed out is that particularly in the field of orthopaedics, the term ‘stem cell’ is used rather loosely,” Einhorn said. “To a molecular biologist, a stem cell is a cell that has the ability to renew itself.”

There are several stem cell types:

“I think most of the cells that we talk about and refer to as ‘stem cells’ in orthopaedics are probably progenitor cells,” Einhorn said. “There has already been some genetic commitment to a particular lineage. To be more accurate, we probably need to talk about osteoprogenitor cells or skeletal progenitor cells or mesenchymal stem cells, which at least qualifies the stem cell as being part of the mesenchymal family.”

Functional potential of MSCs

Mesenchymal stem cells have the ability to differentiate into osteoblasts, chondrocytes and adipocytes and are probably the most commonly used cells in orthopaedics, according to Einhorn.

But there is more to MSCs than being able to differentiate into new cells, according to Wa’el Kafienah, PhD, senior lecturer in stem cell biology at the University of Bristol, in Bristol, United Kingdom.

These cells can offer layers of function, including enhancing the body’s own repair mechanisms and immunosuppressive ability, dampening the immune response to minimize the rejection of transplanted cells or tissues, Kafienah told Orthopaedics Today Europe.

Repair of cartilage damage with MSCs

Overall, researchers have obtained good results with MSCs, Cugat said.

“Clinically, the experience is still small,” he said. “In orthopaedics, there is more experience in the treatment of chondral defects. A large percentage of the population worldwide suffers from osteoarthritis in one or more of their joints.”

“The aim of researchers in regenerative medicine is to repair organs or tissues that are damaged by aging, disease or trauma, such that function is restored or improved,” Gobbi said. “The use of bone marrow derived multipotent MSCs represents a valuable treatment option, especially for the treatment of the degenerative diseases of cartilage,” he said.

Gobbi and colleagues started using bone marrow aspirate concentrate (BMAC) for cartilage repair in 2006. They found that combining BMAC with a scaffold to treat full-thickness cartilage defects achieved good results.

“Therefore, we started treating big defects [in] patients who were referred to total knee replacement (TKR),” Gobbi said. “We started talking about biological arthroplasty.”

Tissue regrowth studied

The results were encouraging and yielded regrown tissue that was similar to normal hyaline cartilage, he said.

In a prospective study, Gobbi and colleagues followed 25 patients who were operated on for grade IV knee cartilage lesions for a minimum period of 3 years. All patients underwent a mini-arthrotomy and concomitant transplantation of a BMAC covered with a collagen matrix. The average lesion the patients had was sized 8.6 cm².

The researchers observed significant improvement in the knee visual analog scale, the objective and subjective portions of the International Knee Documentation Committee (IKDC) scale, the Knee Injury and Osteoarthritis Outcome Scale (KOOS) and the Lysholm scale. The preoperative IKDC subjective score was 41 points and postoperatively it was 82 points, Gobbi said. The preoperative KOOS score was 66 points, which increased to 89 points postoperatively. Furthermore, there were no adverse reactions or serious postoperative complications, he said.

Mesenchymal stem cells are an option for many patients with cartilage defects, regardless of age, according to Gobbi.

“This is a good therapy for patients who are in the gray zone,” he said. “They are not young, [but] they are not so old as to be treated with TKR.” The patients suited for this kind of MSC therapy range in age from 45 years to 55 years, and they are active. Their cartilage has degenerated, and they have a lesion, Gobbi noted.

“They don’t want to go to TKR,” Gobbi said. “We can probably give this patient maybe 15 years or 20 more years before going on to TKR, with a huge difference in terms of cost to society, rehabilitation, etc. These people can go back — not to competitive sport, but to a normal life,” he said.

Clinically, MSC treatment yields cartilage repair results that are quite similar to the standard therapy, autologous chondrocyte implantation (ACI), according to Francesca Vannini, MD, PhD, of the Rizzoli Orthopaedic Institute in Bologna.

However, this procedure is simpler than ACI.

“The mesenchymal cells are more convenient because the procedure can be performed in one step,” Vannini said. And, she said it costs less because MSCs do not require a laboratory phase or a second procedure.

In the literature, Nejdanik and colleagues studied 72 patients matched according to age and lesion size and their results demonstrated that bone marrow-derived stem cells were as effective as ACI for cartilage repair. Those researchers found in their 2010 study that the one-step stem cell-based procedure reduced health care costs and minimized donor-site morbidity.

Osteochondral lesions

A one-step repair that used MSCs to treat talar osteochondral lesions also demonstrated effectiveness. In a study published last year, Giannini and colleagues performed a single-step arthroscopic procedure using bone marrow-derived cells in 49 patients, who achieved good clinical results that persisted over time.

There are some key elements that ensure optimal outcomes with MSC procedures. Precise indications are critical, according to Gobbi.

For example, the surgeon must correct any malalignment before or during surgery. The technique is not well suited for patients who are obese or who have diabetes. In addition, patients must understand that the rehabilitation is long and demanding with strict non-weight bearing for at least 45 days. Gobbi said they cannot return to sports activities for 9 months to 12 months.

“It is not like [getting] a TKR, and then after one month, you go bicycling,” he said.

MSCs to treat hip AVN

There is evidence that MSCs can treat hip avascular necrosis (AVN). The MSCs help cover the dead bone with live bone. The goal is to produce enough bone to maintain the strength and integrity of the femoral head, preventing its collapse, Einhorn said.

Einhorn learned this surgical technique from Philippe Hernigou, MD, who has more than 10 years of experience with the procedure. After returning home from visiting with Hernigou, Einhorn modified the technique a bit and developed instrumentation that helped make the procedure easier to carry out.

Over the years, Hernigou has achieved good results, Einhorn said. “I am just now seeing my results,” he said. One-year results from his prospective case series show that 80% of patients still have intact femoral heads.

Further, that group of patients demonstrated 74% improvement in various pain and function scales.

“In other words, there is a 1 out of 5 chance that the operation is going to fail,” Einhorn said. “If you are in the lucky group of 4 out of 5 [who don’t fail], you can anticipate up to 75% improvement in your pain and function.”

Einhorn’s patients have encountered few complications. “I had one or two patients who had persistent drainage for a few days,” he said. “It was just a little bother that went way in a few days.” He has seen no deep infections, but has seen one major complication. A patient who travelled to Einhorn’s office for treatment broke her hip as she raced through the airport on her return trip home.

Einhorn looks forward to presenting 2-year data on his first 50 patients with AVN treated with MSCs. “Then I can make more robust statements about how well I think the procedure worked,” he added.

Promising indication: Nonunion

Einhorn hopes that in the future MSC indications will expand to other conditions. For instance, he has been using them to treat nonunions. “I have done probably half a dozen to eight cases of fracture nonunion,” Einhorn said. “The results there are quite good.”

Findings from a recent double-blind study done in the United Kingdom by A. Bhattacharjee and colleagues support Einhorn’s work. In that work, he said bone marrow derived stem cells stimulated healing of nonunions in 35 patients.

Some of the most exciting stem cell research, however, is examining the use of MSCs in osteoarthritis and meniscal repair, Cugat said.

Gobbi said his team is testing a new ligament in dogs with Lars Petersen, MD, of Sweden. Other researchers — including Norimasa Nakamura, MD, PhD, of Osaka, Japan, and James Hui, MBBS(Sing), FRCS(Edin), FAMS(Sing), of Singapore — are implanting MSCs without scaffolds. “They are trying to use a [greater] number of cells and seed the cells into the lesion,” he said, referring to a first-in-man clinical trial into repair of tears in the difficult to heal white zone of the meniscus using a stem cell bandage. The trial is being conducted in Bristol by Azellon Therapeutics, Kafienah noted.

What everyone seems to agree on is that a lot more research is necessary before these cells can be used routinely in patients.

“There are several ongoing clinical studies on the use of MSCs, however, there are not prospective double blind controlled studies providing long-term results on the efficacy of mesenchymal stem cells in orthopaedic applications,” Gobbi said. “Additionally,” he said, “the nature, function and regeneration capacity of the so-called adult stem cells are still under investigation from basic scientists, in order to generate safe and effective therapies.”

Unanswered questions

Investigators must resolve some key issues, such as lingering questions about the cells’ efficacy, Einhorn said. “I am sure it depends on the setting,” Einhorn told Orthopaedics Today Europe. “In other words, they may work to heal certain nonunions but not others. They may be effective in the treatment of AVN, but not osteoarthritis.”

What’s more, researchers must find a way to ensure cell potency, Kafienah said.

The other issue is cost, Kafienah noted.

“Especially when you talk about 2-step procedures that involve taking the cells from the patient, expanding them in a clean lab and then returning them to the patient — that is very costly,” he said. “It can cost $10,000 to $20,000” per case.

However, “cost would not be a problem as long as we can identify a potent approach,” Kafienah said. “If MSCs are potent, people will be happy to use them, even if they are costly, because the assumption is that if they work, there will be no further need for care, treatment or drugs.”

Long-term follow-up studies are needed first to figure out what happens to these cells post-implantation, Kafienah said.

Finally, researchers must determine the optimal method for delivering these cells, Einhorn said.

Still, the future looks fairly bright for using MSCs in orthopaedic surgery.

“As our experience and understanding [of stem cells] grows, the indications will increase,” Cugat said. Surgeons will likely rely more on these types of non-drug and non-implant approaches to orthopaedic care because they all know that “regeneration is better than repair,” Cugat said. – by Colleen Owens

• References:
• Bhattacharjee A. ICRS Newsletter. 2012;16:36.
• Caplan A. J Orthop Res. 1991;9:641-650.
• Gangji V. JBJS Essential Surgical Techniques. 2005. doi: 10.2106/JBJS.D.02662.
• Giannini S. Am J Sports Med. 2012. doi:10.1177/0363546512467622.
• Gobbi A. Minerava Ortop Traumatol. 2012;63(Suppl.):127-131.
• Gobbi A. Next generation cartilage solutions. Chapter in: Doral M et al. Sports Injuries: Prevention, Diagnosis, Treatment and Rehabilitation. Berlin: Springer Verlag; 2012:739-749.
• Gobbi A. The use of bone marrow aspirate concentrated for full-thickness knee cartilage lesions in one-step procedure: a prospective study (SS-25). Arthroscopy. 2011;27(5) Supplement: e43.
• Nejadnik H. Am J Sports Med. 2010. doi: 10.1177/0363546509359067.

• For more information:

• Ramon Cugat, MD, PhD, can be reached at Hospital Quiron Barcelona, Plaza Alfonso Comin 5-7, 08023 Barcelona, Spain; email: ramon.cugat@sportrauma.com.
• Thomas A. Einhorn, MD, can be reached at Boston University Orthopaedic Surgical Associates, 725 Albany St., Shapiro 4th Floor, Suite 4B, Boston, MA 02118, USA; email: thomas.einhorn@bmc.org.
• Alberto Gobbi, MD, can be reached at Orthopaedic Arthroscopic Surgery International Bioresearch Foundation, 24 via Amadeo GA, Milan 20133, Italy; email: gobbi@cartilagedoctor.it.
• Wa’el Kafienah, PhD, can be reached at the School of Cellular and Molecular Medicine, University of Bristol, Medical Sciences Building, Bristol BS8 1TD, UK; email: w.z.kafienah@bristol.ac.uk.
• Francesca Vannini, MD, can be reached at Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136 Bologna, Italy; email: Francesca.vannini@ior.it.

Disclosures: Einhorn has stock options with NeoStem and is a paid consultant to Harvest Technology. Gobbi is a consultant for Piramal in Canada. He received a research grant from Harvest Technology. Kafienah is a shareholder in Azellon Therapeutics. Cugat and Vannini have no relevant financial disclosures.

What is the best current delivery method to ensure that mesenchymal stem cells get to the intended target?

Scaffold-free tissue-engineered construct ideal

The key issues for success in stem cell therapy are the safety and cost-effectiveness, in addition to biological activities (proliferation and differentiation) of the delivered cells. In this regard, I believe a scaffold-free tissue engineered construct (TEC) is one of the best methods to locally deliver mesenchymal stem cells (MSCs).

The TEC contains MSCs at high density within a 3-D collagen rich matrix that is synthesized by the cells. No animal or chemical materials are used. Therefore, in terms of safety and cost effectiveness, the TEC has advantages over MSCs in “scaffolds” because there is no need to use extrinsic biomaterials.

On the other hand, the TEC is rich in adhesion molecules such as fibronectin and has adhesive property to various tissues and, therefore, a simple implantation procedure is available with a short duration without any reinforcement needed for fixation. Finally, the TEC has strong multi-differentiation capacity, including the ability to differentiate into bone, cartilage and adipose tissue.

Based on such biological properties, the feasibility of the TEC for tissue repair has been demonstrated in various musculoskeletal tissues, such as cartilage, as noted in studies by Ando and Shimomura and colleagues, the meniscus, as Moriguchi and colleagues showed, the growth plate, based on work that Yoshida and colleagues did, and the intervertebral disc, which Moriguchi presented results of at the Orthopaedic Research Society Annual Meeting this year. The TEC can be a promising bioimplant for the future of regenerative medicine using stem cells in musculoskeletal tissues.

Norimasa Nakamura, MD, PhD, is at Institute for Medical Science in Sports, Osaka Health Science University, in Osaka, Japan.
Disclosure: Nakamura has no relevant financial disclosures.

References:

Ando W. Biomaterials. 2007;28:5462-5470.

Moriguchi Y. Biomaterials. 2013. doi: 10.1016/j.biomaterials.2012.11.039.

Moriguchi Y. Paper #847. Presented at: Orthopaedic Research Society Annual Meeting; Jan. 26-29, 2013; San Antonio, Texas.

Shimomura K. Biomaterials. 2010. doi: 10.1016/j.biomaterials.2010.07.017.

Yoshida K. J Pediatr Orthop. 2012. doi: 10.1097/BPO.0b013e31824afee3.

3-D scaffold is the best choice

The high regenerative potential and the capacity of differentiation of bone marrow mononuclear cells makes them suitable for multiple indications in orthopaedic pathology, especially where injured osseous or chondral tissue is not healing well or shows the healing potential. These cells can be both harvested and implanted in a single-step technique.

The best way to deliver these cells into the lesion site is with the help of a 3-D scaffold, which can be loaded with the stem cells and directly implanted. There are different biomaterials for this. We currently use a disposable kit for the whole procedure, which includes aspiration of the cells from the iliac crest, and their concentration and implantation (IOR-G1; Novagenit Srl, Mezzolombardo, TN, Italy). The biomaterial included in this kit is a collagen membrane, which is particularly useful because it drives the differentiation of the stem cells into osteoblasts and chondrocytes.

When an osteochondral defect is treated with stem cells it is possible to use an arthroscopic technique with specifically designed instrumentation to deliver them, with the advantages of this being less surgical trauma and a faster postoperative recovery.

Sandro Giannini, MD, is director of Clinica Ortopedica e Traumatologica II at Istituto Ortopedico Rizzoli in Bologna, Italy.
Disclosure: Giannini has no relevant financial disclosures.