Systematic review assessing the evidence for the use of stem cells in fracture healing

Cell-based therapy in the treatment of musculoskeletal diseases

A limited number of tissues can spontaneously regenerate following injury, and even fewer can regenerate to a state comparable to mature, healthy adult tissue. Mesenchymal stem cells (MSCs) were first described in the 1960s-1970s by Friedenstein et al as a small population of bone marrow cells with osteogenic potential and abilities to differentiate into chondrocytes. In 1991, Arnold Caplan coined the term "mesenchymal cells" after identifying these cells as a theoretical precursor to bone, cartilage, tendon, ligament, marrow stroma, adipocyte, dermis, muscle, and connective tissues. MSCs are derived from periosteum, fat, and muscle. Another attractive property of MSCs is their immunoregulatory and regenerative properties, which result from crosstalk with their microenvironment and components of the innate immune system. Collectively, these properties make MSCs potentially attractive for various therapeutic purposes. MSCs offer potential in sports medicine, aiding in muscle recovery, meniscal tears, and tendon and ligament injuries. In joint disease, MSCs have the potential for chondrogenesis and reversing the effects of osteoarthritis. MSCs have also demonstrated potential application to the treatment of degenerative disc disease of the cervical, thoracic, and lumbar spine.

Advanced Therapeutic Medicinal Products in Bone and Cartilage Defects

The number of patients with functional loss of bone and cartilage tissue has shown an increasing trend. Insufficient or inappropriate conventional treatments applied for trauma, orthopedic diseases, or other bone and cartilage-related disorders can lead to bone and cartilage damage. This represents a worldwide public health issue and a significant economic burden. Advanced therapeutic medicinal products (ATMPs) proposed promising alternative therapeutic modalities by application of cell-based and tissue engineering approaches. Recently, several ATMPs have been developed to promote bone and cartilage tissue regeneration. Fifteen ATMPs, two related to bone and 13 related to cartilage, have received regulatory approval and marketing authorization. However, four ATMPs were withdrawn from the market for various reasons. However, ATMPs that are still on the market have demonstrated positive results, their broad application faced limitations. The development and standardization of methodologies will be a major challenge in the coming decades. Currently, the number of ATMPs in clinical trials using mesenchymal stromal cells or chondrocytes indicates a growing recognition that current ATMPs can be improved. Research on bone and cartilage tissue regeneration continues to expand. Cell-based therapies are likely to be clinically supported by the new ATMPs, innovative fabrication processes, and enhanced surgical approaches. In this study, we highlighted the available ATMPs that have been used in bone and cartilage defects and discussed their advantages and disadvantages in clinical applications.

Biological aspects to enhance fracture healing

The ability to enhance fracture healing is paramount in modern orthopaedic trauma, particularly in the management of challenging cases including peri-prosthetic fractures, non-union and acute bone loss. Materials utilised in enhancing fracture healing should ideally be osteogenic, osteoinductive, osteoconductive, and facilitate vascular in-growth. Autologous bone graft remains the gold standard, providing all of these qualities. Limitations to this technique include low graft volume and donor site morbidity, with alternative techniques including the use of allograft or xenograft. Artificial scaffolds can provide an osteoconductive construct, however fail to provide an osteoinductive stimulus, and frequently have poor mechanical properties. Recombinant bone morphogenetic proteins can provide an osteoinductive stimulus; however, their licencing is limited and larger studies are required to clarify their role. For recalcitricant non-unions or high-risk cases, the use of composite graft combining the above techniques provides the highest chances of successfully achieving bony union.

Intraoperative Creation of Tissue-Engineered Grafts with Minimally Manipulated Cells: New Concept of Bone Tissue Engineering In Situ

Transfer of regenerative approaches into clinical practice is limited by strict legal regulation of in vitro expanded cells and risks associated with substantial manipulations. Isolation of cells for the enrichment of bone grafts directly in the Operating Room appears to be a promising solution for the translation of biomedical technologies into clinical practice. These intraoperative approaches could be generally characterized as a joint concept of tissue engineering in situ. Our review covers techniques of intraoperative cell isolation and seeding for the creation of tissue-engineered grafts in situ, that is, directly in the Operating Room. Up-to-date, the clinical use of tissue-engineered grafts created in vitro remains a highly inaccessible option. Fortunately, intraoperative tissue engineering in situ is already available for patients who need advanced treatment modalities.

Different Protocols of Combined Application of Photobiomodulation In Vitro and In Vivo Plus Adipose-Derived Stem Cells Improve the Healing of Bones in Critical Size Defects in Rat Models

Introduction: Long bone segmental deficiencies are challenging complications to treat. Hereby, the effects of the scaffold derived from the human demineralized bone matrix (hDBMS) plus human adipose stem cells (hADSs) plus photobiomodulation (PBM) (in vitro and or in vivo) on the catabolic step of femoral bone repair in rats with critical size femoral defects (CDFDs) were evaluated with stereology and high stress load (HSL) assessment methods. Methods: hADSs were exposed to PBM in vitro; then, the mixed influences of hDBMS+hADS+PBM on CSFDs were evaluated. CSFDs were made on both femurs; then hDBMSs were engrafted into both CSFDs of all rats. There were 6 groups (G)s: G1 was the control; in G2 (hADS), hADSs only were engrafted into hDBMS of CSFD; in G3 (PBM) only PBM therapy for CSFD was provided; in G4 (hADS+PBM in vivo), seeded hADSs on hDBMS of CSFDs were radiated with a laser in vivo; in G5 (hADSs+PBM under in vitro condition), hADSs in a culture system were radiated with a laser, then transferred on hDBMS of CSFDs; and in G6 (hADS+PBM in conditions of in vivo and in vitro), laser-exposed hADSs were transplanted on hDBMS of CSFDs, and then CSFDs were exposed to a laser in vivo. Results: Groups 4, 5, and 6 meaningfully improved HSLs of CSFD in comparison with groups 3, 1, and 2 (all, P=0.001). HSL of G5 was significantly more than G4 and G6 (both, P=0.000). Gs 6 and 4 significantly increased new bone volumes of CSFD compared to Gs 2 (all, P=0.000) and 1 (P=0.001 & P=0.003 respectively). HSL of G 1 was significantly lower than G5 (P=0.026). Conclusion: HSLs of CSFD in rats that received treatments of hDBMS plus hADS plus PBM were significantly higher than treatments with hADS and PBM alone and control groups.

Autologous versus synthetic bone grafts for the surgical management of tibial plateau fractures: a systematic review and meta-analysis of randomized controlled trials

AIMS

Our objective was to conduct a systematic review and meta-analysis, to establish whether differences arise in clinical outcomes between autologous and synthetic bone grafts in the operative management of tibial plateau fractures.

METHODS

A structured search of MEDLINE, EMBASE, the online archives of Bone & Joint Publishing, and CENTRAL databases from inception until 28 July 2021 was performed. Randomized, controlled, clinical trials that compared autologous and synthetic bone grafts in tibial plateau fractures were included. Preclinical studies, clinical studies in paediatric patients, pathological fractures, fracture nonunion, or chondral defects were excluded. Outcome data were assessed using the Risk of Bias 2 (ROB2) framework and synthesized in random-effect meta-analysis. The Preferred Reported Items for Systematic Review and Meta-Analyses guidance was followed throughout.

RESULTS

Six studies involving 353 fractures were identified from 3,078 records. Following ROB2 assessment, five studies (representing 338 fractures) were appropriate for meta-analysis. Primary outcomes showed non-significant reductions in articular depression at immediate postoperative (mean difference -0.45 mm, p = 0.25, 95%confidence interval (CI) -1.21 to 0.31, I2 = 0%) and long-term (> six months, standard mean difference -0.56, p = 0.09, 95% CI -1.20 to 0.08, I2 = 73%) follow-up in synthetic bone grafts. Secondary outcomes included mechanical alignment, limb functionality, and defect site pain at long-term follow-up, perioperative blood loss, duration of surgery, occurrence of surgical site infections, and secondary surgery. Mean blood loss was lower (90.08 ml, p < 0.001, 95% CI 41.49 to 138.67) and surgery was shorter (16.17 minutes, p = 0.04, 95% CI 0.39 to 31.94) in synthetic treatment groups. All other secondary measures were statistically comparable.

CONCLUSION

All studies reported similar methodologies and patient populations; however, imprecision may have arisen through performance variation. These findings supersede previous literature and indicate that, despite perceived biological advantages, autologous bone grafting does not demonstrate superiority to synthetic grafts. When selecting a void filler, surgeons should consider patient comorbidity, environmental and societal factors in provision, and perioperative and postoperative care provision. Cite this article: Bone Jt Open 2022;3(3):218-228.

Effects of Collagen- and Arginine-Fortified Osteokine Supplementation on Fracture Healing

Introduction

Delayed union or nonunion is an important clinical challenge for orthopedic surgeons. In addition to the main treatment algorithms, the use of nutritional supplements is increasingly common. In this study, we investigated the effects of nutritional supplements fortified with arginine and collagen on fracture healing.

Materials and methods

Twenty-four rats with femur fractures were divided into experimental and control groups. Intramedullary fixation was performed in both groups. 20 ml/kg nutritional supplement was given to the experimental group. Radiological examination was performed at third and sixth weeks, and histopathological examination was performed at the sixth week.

Results

No statistically significant difference was found between the radiological scores of the groups at the third and sixth weeks. Nutritional supplement affected the histological properties of callus. Histological evidence of bone healing was observed by the sixth week in both groups but the score was higher in nutritional supplement group. A statistically significant difference was found between the histopathological scores of the groups at the sixth week.

Conclusion

Arginine- and type two collagen-augmented traditional nutritional supplements may help to achieve more successful results in fracture healing.

Proteomic Comparison of Bone Marrow Derived Osteoblasts and Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) can differentiate into osteoblasts, and therapeutic targeting of these cells is considered both for malignant and non-malignant diseases. We analyzed global proteomic profiles for osteoblasts derived from ten and MSCs from six healthy individuals, and we quantified 5465 proteins for the osteoblasts and 5420 proteins for the MSCs. There was a large overlap in the profiles for the two cell types; 156 proteins were quantified only in osteoblasts and 111 proteins only for the MSCs. The osteoblast-specific proteins included several extracellular matrix proteins and a network including 27 proteins that influence intracellular signaling (Wnt/Notch/Bone morphogenic protein pathways) and bone mineralization. The osteoblasts and MSCs showed only minor age- and sex-dependent proteomic differences. Finally, the osteoblast and MSC proteomic profiles were altered by ex vivo culture in serum-free media. We conclude that although the proteomic profiles of osteoblasts and MSCs show many similarities, we identified several osteoblast-specific extracellular matrix proteins and an osteoblast-specific intracellular signaling network. Therapeutic targeting of these proteins will possibly have minor effects on MSCs. Furthermore, the use of ex vivo cultured osteoblasts/MSCs in clinical medicine will require careful standardization of the ex vivo handling of the cells.

Stem Cell Therapy in the Management of Fracture Non-Union - Evaluating Cellular Mechanisms and Clinical Progress

Bone, as a physiological and anatomical construct, displays remarkable intrinsic healing capacity. The overwhelming majority of fractures will heal satisfactorily, if aligned anatomically, compressed and immobilised appropriately. Of the 10% of fractures that do not heal, even under ideal mechanical and biological conditions, further consideration must be given to augment bone healing. Management strategies for non-union pose a significant clinical challenge to the practicing orthopaedic surgeon. Stem cell therapy is beginning to demonstrate significant potential for augmented bone repair in the context of non-union. This review attempts to contextualise the function of stem cells within this clinical setting, reviewing the relevant cellular mechanisms and clinical applications. From evaluating the literature base, there is a lack of high-quality evidence examining the role of mesenchymal stem cells (MSCs) within this research focus. Appropriately designed randomised controlled trials are required to evaluate this research area further, with a view to guiding future treatment options for the practicing orthopaedic surgeon.