Evaluation of the effects of the combination of autologous mesenchymal stem cells and platelet-rich plasma on structural bone allograft healing

Optimal delivery of endothelial progenitor cells in a rat model of critical-size bone defects

Nonunion and segmental bone defects are complex issues in orthopedic trauma. The use of endothelial progenitor cells (EPCs), as part of a cell-based therapy for bone healing is a promising approach. In preclinical studies, culture medium (CM) is commonly used to deliver EPCs to the defect site, which has the potential for immunogenicity in humans. The goal of this study was to find an effective and clinically translatable delivery medium for EPCs. Accordingly, this study compared EPCs delivered in CM, phosphate-buffered saline (PBS), platelet-poor plasma (PPP), and platelet-rich plasma (PRP) in a rat model of femoral critical-size defects. Fischer 344 rats (n = 35) were divided into six groups: EPC+CM, EPC+PBS, EPC+PPP, EPC+PRP, PPP alone, and PRP alone. A 5 mm mid-diaphyseal defect was created in the right femur and stabilized with a miniplate. The defect was filled with a gelatin scaffold impregnated with the corresponding treatment. Radiographic, microcomputed tomography and biomechanical analyses were performed. Overall, regardless of the delivery medium, groups that received EPCs had higher radiographic scores and union rates, higher bone volume, and superior biomechanical properties compared to groups treated with PPP or PRP alone. There were no significant differences in any outcomes between EPC subgroups or between PPP and PRP alone. These results suggest that EPCs are effective in treating segmental defects in a rat model of critical-size defects regardless of the delivery medium used. Consequently, PBS could be the optimal medium for delivering EPCs, given its low cost, ease of preparation, accessibility, noninvasiveness, and nonimmunogenic properties.

Novel applications of platelet concentrates in tissue regeneration (Review)

Numerous studies have explored the suitability of biocompatible materials in regenerative medicine. Platelet concentrates are derived from centrifuged blood and are named according to their biological characteristics, such as platelet-rich plasma, platelet-rich fibrin and concentrated growth factor. Platelet concentrates have gained considerable attention in soft and hard tissue engineering. Indeed, multiple components of autologous platelet concentrates, such as growth factors, fibrin matrix and platelets, serve essential roles in wound healing. Current studies are focused on cutting-edge strategies to meet the requirements for tissue restoration by improving the properties of autologous platelet concentrates. In the present review, applications of platelet concentrates for tissue engineering are discussed, presenting a selection of recent advances and novel protocols. In addition, several aspects of these strategies, such as the advantages of lyophilized platelet concentrates and the combination of platelet concentrates with biomaterials, stem cells or drugs are discussed. The present review aims to summarize novel strategies using platelet concentrates to improve the outcomes of wound healing.

The platelet-rich plasma and mesenchymal stem cell milieu: A review of therapeutic effects on bone healing

Platelet-rich plasma is autologous plasma that contains concentrated platelets compared to whole blood. It is relatively inexpensive to produce, can be easily isolated from whole blood, and can be administered while the patient is in the operating room. Further, because platelet-rich plasma is an autologous therapy, there is minimal risk for adverse reactions to the patient. Platelet-rich plasma has been used to promote bone regeneration due to its abundance of concentrated growth factors that are essential to wound healing. In this review, we summarize the methods for producing platelet-rich plasma and the history of its use in bone regeneration. We also summarize the growth factor profiles derived from platelet-rich plasma, with emphasis on those factors that play a direct role in promoting bone repair within the local fracture environment. In addition, we discuss the potential advantages of combining platelet-rich plasma with mesenchymal stem cells, a multipotent cell type often obtained from bone marrow or fat, to improve craniofacial and long bone regeneration. We detail what is currently known about how platelet-rich plasma influences mesenchymal stem cells in vitro, and then highlight the clinical outcomes of administering platelet-rich plasma and mesenchymal stem cells as a combination therapy to promote bone regeneration in vivo.

Is Ebselen A Therapeutic Target in Fracture Healing?

Objective

We investigated the effect of ebselen on fracture healing in an experimental fracture model.

Materials and Methods

We divided rats into two groups, 6 rats in each: the experimental femur fracture control group and the ebselen treatment group with an experimental femur fracture. In the experimental femur fracture control group, we created only experimental femur fracture. In the ebselen treatment group, we administered ebselen treatment with creating an experimental femur fracture. We administered ebselen intraperitoneally at 5 mg/kg once daily for 1 month after the 1st day of experimental femur fracture in the ebselen treatment group. We evaluated the recovery status of fractured femurs at the end of 1st month with radiographic, histopathological, and immunohistochemical methods.

Results

According to the radiographic fracture healing scores, ebselen treatment increased the extent of new bone formation and fracture cartilage callus significantly compared to the control group. According to the histopathological recovery scores, ebselen treatment significantly improved healing scores compared to the control group. Ebselen treatment increased the expression scores of bone healing markers in the ebselen treatment group, such as vascular endothelial growth factor and osteocalcin, compared to the control group.

Conclusion

We demonstrated that ebselen treatment increases the formation of new bone in the femur in an experimentally created femoral fracture model. Ebselen has been shown to improve the bone fracture healing in a radiological and histopathological manner, and more detailed studies are needed.

A New Method for Partial Breast Reconstruction: 3-Year New Zealand Experience

In New Zealand, oncoplastic surgery is common, but partial breast reconstruction presents challenges for radiation therapy targeting. Tissue rearrangement creates ambiguity when targeting the tumor bed, with resultant overestimation of treatment volumes. Thus, adoption of advanced methods of radiation therapy have been hindered. This pilot study describes use of a novel three-dimensional implant that provides a scaffolding for tissue ingrowth during partial breast reconstruction and delineates the tumor bed more precisely to assist radiation planning and mammographic surveillance. After informed consent, 15 women were implanted with the three-dimensional bioabsorbable implant. The device was sutured to the tumor bed during lumpectomy, and tissue flaps were mobilized and attached to the implant. Visualization of the marker and radiation treatment volumes were recorded and compared. The implant provided volume replacement and helped to maintain breast contour. Cosmetic outcomes were excellent; no device- or radiation-related complications occurred. One patient had a postoperative hematoma that resolved after percutaneous drainage; there were no postoperative infections. Three-year follow-up shows no tumor recurrences and no untoward effects. When compared to conventional radiation targeting, use of the implant showed that a greater than 50 percent reduction in treatment volume was possible in some cases. Three-year mammograms show no significant artifact, normal tissue ingrowth, and minimal fibrosis. This study describes a method of oncoplastic breast reconstruction using an implantable device that marks the site of tumor excision and provides for volume replacement with tissue ingrowth. Patients tolerated it well, and radiation therapy planning, positioning, and treatment were facilitated.

Nasal Dorsal Augmentation with Freeze-Dried Allograft Bone: 10-Year Comprehensive Review

Supplemental Digital Content is available in the text.

Background:

The aim of this study was to evaluate freeze-dried cortical allograft bone for nasal dorsal augmentation. The 42-month report on 18 patients was published in 2009 in Plastic and Reconstructive Surgery with 89 percent success at level II evidence, and this article is the 10-year comprehensive review of 62 patients.

Methods:

All grafts met standards recommended by the American Association of Tissue Banks, the U.S. Food and Drug Administration, and the Centers for Disease Control and Prevention. Objective evaluation of the persistence of graft volume was obtained by cephalometric radiography, cone beam volumetric computed tomography, and computed tomography at up to 10 years. Vascularization and incorporation of new bone elements within the grafts were demonstrated by fluorine-18 sodium fluoride positron emission tomography at up to 10 years. Subjective estimation of graft volume persisting up to 10 years was obtained by patient response to a query conducted by an independent surveyor.

Results:

The authors report objective proof of persistence of volume alone or combined with proof of neovascularization in 16 of 19 allografts. The authors report the patient’s subjective opinion of volume persistence in 37 of 43 grafts. The dorsal augmentation was assessed overall to be successful in 85 percent of 62 patients evaluated between 1 and 10 years, with a mean of 4.7 years.

Conclusions:

Freeze-dried allograft bone is a safe and equal alternative for dorsal augmentation without donor-site morbidity. Further studies are needed to (1) confirm these findings for young patients needing long-term reconstruction, and (2) partially demineralize allograft bone to allow carving with a scalpel.

CLINICAL QUESTION/LEVEL OF EVIDENCE:

Therapeutic, IV.

Platelet-rich plasma lyophilization enables growth factor preservation and functionality when compared with fresh platelet-rich plasma

Aims: To compare levels and activity of the growth factors between fresh and lyophilized platelet-rich plasma (PRP). Methods: Analysis of platelet concentration using fibroblast and human umbilical vein endothelial cell cultures were compared between fresh and lyophilized PRP obtained from peripheral blood. Results: After lyophilization, 54% of platelets were intact whereas the fresh showed no aggregation with agonists (levels under 20%). The concentration of growth factors (VEGF, EGF, TGF-β and PDGF) in both products were similar. Fresh and lyophilized PRPs induced proliferation in the fibroblasts at 24 h (0.303 vs 0.300, respectively). Conclusion: Lyophilized PRP appears to be an alternative to fresh PRP and the results evidenced the role of growth factors as a key element in the activity of this product.

Evaluation of the effects of the combination of BMP-2-modified BMSCs and PRP on cartilage defects

Articular cartilage is avascular and aneural, and has limited capacity for self-regeneration when injured. Tissue engineering has emerged as a promising approach in repairing cartilage defects. To improve the therapy of cartilage healing, the present study investigated the efficacy of the combination of lentivirus-mediated bone morphogenetic protein-2 (BMP2) in bone marrow-derived stromal cells (BMSCs) and platelet-rich plasma (PRP) on cartilage and bone healing in a cartilage defect model using the rabbit knee. The BMSCs were harvested from New Zealand rabbits and transduced with lentivirus carrying BMP-2. Standard bone defects were introduced in the femoral groove of patellofemoral joints of 48 New Zealand rabbits. The cartilage defects were subjected to synthetic scaffold mosaicplasty with chitosan/silk fibroin/nanohydroxyapatite particles tri-component scaffolds soaked in BMSCs and PRP. After 16 weeks, the tissue specimens were assessed by micro-computed tomography (micro-CT) and macroscopic examination. The results showed that lentivirus-mediated BMP-2 and PRP increased the cell viability of the BMSCs, induced the expression of associated genes and enhanced osteogenic differentiation in vitro. In vivo, the expression of BMP-2 was observed for 16 weeks. The combination of BMP-2 and PRP treatment led to optimal results, compared with the other groups on micro-CT and gross observations. The results of the present study present a novel therapy using the lentivirus-mediated BMP-2 gene together with PRP for cartilage healing.