Claudia Di Bella

Stromal stem cells and platelet-rich plasma improve bone allograft integration.

Early vascular invasion is a key factor in bone allograft incorporation. It may reduce the complications related to slow and incomplete bone integration. Bone-marrow-derived stromal stem cells associated with platelet-rich plasma are potent angiogenic inducers proven to release vascular endothelial growth factor. Our goal was to test whether the combination of stromal stem cells and platelet-rich plasma is able to increase massive allograft integration in a large animal model with sacrifice at 4 months. A critical defect was made in the mid-diaphysis of the metatarsal bone of 10 sheep; the study group received an allograft plus stromal stem cells, platelet-rich plasma, and collagen (six animals) and the control group received only the allograft (four animals). Investigation was done with radiographs, mechanical tests and histomorphometric analysis, including new vascularization. Results showed substantial new bone formation in the allograft of the study group. Bone formation is correlated with better vascular invasion and remodeling of the graft in the study group. These results confirm the key role played by stromal stem cells and platelet-rich plasma in bone repair. Further studies are needed to better define the role stromal stem cells play when implanted alone.

Bone Regeneration in a Rabbit Critical-Sized Skull Defect Using Autologous Adipose-Derived Cells

Repair of substantial cranial defects in adults and children may be compromised due to limitations in donor bone stocks for autologous grafts. We evaluated the capability of autologous adipose-derived mesenchymal cells (ADCs) in combination with polylactic acid (PLA) scaffolds to regenerate bone in a critical-sized skull defect. Thirty adult New Zealand White rabbits were divided into six groups of five animals each: (1) PLA alone (control), (2) fibronectin-coated PLA, (3) PLA with ADCs, (4) fibronectin-coated PLA with ADCs, (5) PLA with osteogenically induced ADCs (osADCs), and (6) fibronectin-coated PLA with osADCs. All the animals were humanely killed after 6 weeks. X-ray, histology, and histomorphometric analysis were performed to evaluate the new bone formation inside the PLA scaffold. Radiographically and histomorphometrically, the groups in which the PLA was not fibronectin coated showed no bone formation in contrast to the fibronectin-coated groups (Gp1 vs. Gp2, p < 0.0005); the group treated with osteo-induced ADCs and fibronectin (Gp6) showed significantly more bone formation than the group treated with undifferentiated ADCs (Gp4) and the group treated without cells (Gp5, p < 0.0005, in both cases). These data indicate that the surface treatment with fibronectin promotes bone formation within the scaffold, and that autologous, osteo-induced adipose-derived cells enhance bone formation if seeded into a fibronectin-treated PLA scaffold.

Allograft-Prosthetic Composite in the Proximal Tibia After Bone Tumor Resection

AbstractWe consider an allograft-prosthesis composite in the proximal tibia one of the better reconstructive options in this site because it combines the mechanical stability of a prosthesis with the biologic reconstruction of the extensor mechanism. We retrospectively reviewed 62 patients who had proximal tibia reconstructions with allograft-prosthesis composites to ascertain the complications and functional outcomes. By combining an allograft with a prosthesis, placing cement in the graft, and press-fitting the prosthesis in the tibial diaphysis, we obtained satisfactory Musculoskeletal Tumor Society scores in 90.4% of patients, with a 5-year survival rate (73.4%) comparable to that of reconstruction with a modular prosthesis. However, we observed high infection rates (24.2%) and rotation of the medial gastrocnemius seemed not to reduce this complication. For this reason, we do not recommend using this reconstructive technique in patients who will receive postoperative chemotherapy or in patients in whom a previous reconstructive method failed. We believe the ideal candidate is the young patient with a benign aggressive or malignant low-grade tumor who has not undergone previous surgery. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

18F-FDG PET response to neoadjuvant chemotherapy for Ewing sarcoma and osteosarcoma are different

ObjectiveEwing sarcoma (ES) and osteosarcoma (OS) have different biological characteristics and respond differently to chemotherapy. We reviewed 18F-FDG PET imaging characteristics of ES and OS patients at baseline and following treatment to determine whether this biological variation is reflected in their imaging phenotype.Materials and methodsA retrospective review of ES and OS patients treated with neoadjuvant chemotherapy and surgery was done, correlating PET results with histologic response to chemotherapy.ResultsChange in the maximum standardized uptake value (SUVmax) between baseline and post-treatment scanning was not significantly associated with histologic response for either ES or OS. Metabolic tumor volume (MTV) and the percentage of injected 18F-FDG dose (%ID) in the primary tumor were found to be different for ES and OS response subgroups. A 50% reduction in MTV (MTV2:1 < 0.5) was found to be significantly associated with favorable histologic response in OS. Using the same criteria for ES incorrectly predicted good responders. Increasing the cut-off values for ES to a 90% reduction in MTV (MTV2:1 < 0.1) resulted in association with favorable histologic response.ConclusionResponse to neoadjuvant chemotherapy as reflected by changes in PET characteristics should be interpreted differently for ES and OS.

The Posterior Iliac Crest Outperforms the Anterior Iliac Crest When Obtaining Mesenchymal Stem Cells from Bone Marrow

BACKGROUND The clinical application of freshly isolated connective-tissue progenitors, as well as the potential preparation of culture-expanded mesenchymal stem cell populations for therapeutic applications, will benefit from clinical methods that maximize the yield of the starting population. We compared the number of cells, concentration, and prevalence of colony-founding connective-tissue progenitors from the anterior and posterior iliac crest. In addition, we compared the expansion kinetics and multilineage differentiation potential of their culture-expanded progeny when processed to form mesenchymal stem cells. METHODS Marrow aspirate was collected from both the anterior and posterior iliac crest of twenty-two patients. The concentration and prevalence of colony-founding connective-tissue progenitors were estimated with use of a colony formation assay. The expansion kinetics and multilineage differentiation potential of the culture-expanded mesenchymal stem cell populations derived from these starting samples were compared. RESULTS The yield of colony-founding connective-tissue progenitors was 1.6 times greater in the posterior compared with the anterior iliac crest. No differences were found with respect to the viability, phenotype, expansion kinetics, or multilineage differentiation potential of mesenchymal stem cell populations derived from these two sites. CONCLUSIONS The concentration and yield of colony-founding connective-tissue progenitors were greater when aspirate was obtained from the posterior compared with the anterior iliac crest, whereas the biological potential of the cells derived from these sites appeared comparable. CLINICAL RELEVANCE The harvesting of bone marrow from the posterior iliac crest appears to be preferred, as it provided a modestly higher concentration of colony-founding connective-tissue progenitors than comparable aspirate from the anterior iliac crest.

3D Bioprinting of Cartilage for Orthopedic Surgeons: Reading between the Lines.

Chondral and osteochondral lesions represent one of the most challenging and frustrating scenarios for the orthopedic surgeon and for the patient. The lack of therapeutic strategies capable to reconstitute the function and structure of hyaline cartilage and to halt the progression toward osteoarthritis has brought clinicians and scientists together, to investigate the potential role of tissue engineering as a viable alternative to current treatment modalities. In particular, the role of bioprinting is emerging as an innovative technology that allows for the creation of organized 3D tissue constructs via a “layer-by-layer” deposition process. This process also has the capability to combine cells and biomaterials in an ordered and predetermined way. Here, we review the recent advances in cartilage bioprinting and we identify the current challenges and the directions for future developments in cartilage regeneration.

Mesenchymal stem cells and platelet lysate in fibrin or collagen scaffold promote non-cemented hip prosthesis integration

The objective of this study was to evaluate whether mesenchymal stem cells (MSC) and platelet lysate (PL) seeded in a fibrin or collagen scaffold could improve the new bone (NB) formation around an uncemented hip prosthesis stem in a sheep model. In vitro expanded MSC were suspended in PL and either mixed with collagen or fibrin gel as delivery vehicle. The cell–gel composites were inserted inside the femoral canal, then the prosthesis was press‐fit inserted inside the femur. Identical procedures were performed in a control group, but only the prosthesis was implanted. Histomorphometrical analysis performed 4 months after surgery indicated that the newly formed bone inside the medullary canal, between the inner cortex and the prosthetic stem, was significantly higher in the MSC–PL–collagen group (mean 18.7 ± 4.5%) and in the MSC–PL–fibrin group (mean 18.8 ± 15.2%) when compared to the control group (mean 4.6 ± 2.0%). There was a significantly higher bone–prosthesis contact in the MSC–PL–collagen group (mean 2.7 ± 2.6%) and in the MSC–PL–fibrin group (mean 2.3 ± 3.1%) compared to the control group (mean 0.2 ± 0.1%). The results indicate that MSC and PL in a fibrin or collagen scaffold can promote NB formation around an uncemented hip prosthesis stem.

Bioengineering of articular cartilage: past, present and future

The treatment of cartilage defects poses a clinical challenge owing to the lack of intrinsic regenerative capacity of cartilage. The use of tissue engineering techniques to bioengineer articular cartilage is promising and may hold the key to the successful regeneration of cartilage tissue. Natural and synthetic biomaterials have been used to recreate the microarchitecture of articular cartilage through multilayered biomimetic scaffolds. Acellular scaffolds preserve the microarchitecture of articular cartilage through a process of decellularization of biological tissue. Although promising, this technique often results in poor biomechanical strength of the graft. However, biomechanical strength could be improved if biomaterials could be incorporated back into the decellularized tissue to overcome this limitation.

Alloprosthetic Composite is a Suitable Reconstruction After Periacetabular Tumor Resection

BackgroundResection of a tumor of the pelvis is most disabling when the acetabulum is excised and a durable reconstruction of the defect is hard to achieve. All available methods are associated with frequent complications. Few large series have been published, and fewer have focused entirely on complete resections of the acetabulum. The use of an allograft-prosthetic composite allows customization on the operating table. However, while such composites restore anatomy and function of the pelvis the use of pelvic allografts is controversial and the durability is unknown.Questions/purposesWe therefore examined (1) the frequency of allograft and prosthetic failure, (2) positive and negative factors influencing the survival of the allograft prosthetic composite, and (3) function of patients with this reconstruction.Patients and MethodsWe retrospectively evaluated 35 patients who had resection of the entire acetabulum and reconstruction with an allograft-prosthetic composite. Function was scored by the Musculoskeletal Tumor Society system. Followup in 24 survivors averaged 120 months (range, 61–188 months).ResultsGreater than 75% of the allografts were still in place at last followup, and the original prosthetic reconstruction was still in place in 56%. Infection was an important negative factor for allograft survival. The average functional score was 72%, with better mean scores for patients who had reconstruction with a stemmed cup and an artificial ligament (average 89%).ConclusionsAn allograft-prosthetic composite provides a versatile substitution of the pelvis and hip, with functional scores approximately 75% of normal.Level of EvidenceLevel IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Efficient isolation and enrichment of mesenchymal stem cells from bone marrow

BACKGROUND AIMS Bone marrow (BM) mesenchymal stromal cells (MSC) have been identified as a source of pluripotent stem cells used in clinical practice to regenerate damaged tissues. BM MSC are commonly isolated from BM by density-gradient centrifugation. This process is an open system that increases the risk of sample contamination. It is also time consuming and requires technical expertise that may result in variability regarding cellular recovery. The BD Vacutainer® Cell Preparation Tube™ (CPT) was conceived to separate mononuclear cells from peripheral blood. The main goal of this study was to verify whether MSC could be isolated from BM using the CPT. METHODS BM was harvested, divided into two equal aliquots and processed using either CPT or a Ficoll-Paque™ PREMIUM density gradient. Both methods were compared regarding cell recovery, viability, proliferation, differentiation capacities and the presence of MSC progenitors. RESULTS Similar numbers of mononuclear cells were isolated from BM when comparing the two methods under study. No differences were found in terms of phenotypic characterization, viability, kinetics and lineage differentiation potential of MSC derived by CPT or Ficoll. Surprisingly, a fibroblast-colony-forming unit (CFU-F) assay indicated that, with CPT, the number of MSC progenitors was 1.8 times higher compared with the Ficoll gradient separation. CONCLUSIONS The CPT method is able to isolate MSC efficiently from BM, allowing the enrichment of MSC precursors.