A regenerative approach for bone repair in congenital pseudarthrosis of the tibia associated or not associated with type 1 neurofibromatosis: correlation between laboratory findings and clinical outcome

Revolutionizing bone defect healing: the power of mesenchymal stem cells as seeds

Bone defects can arise from trauma or pathological factors, resulting in compromised bone integrity and the loss or absence of bone tissue. As we are all aware, repairing bone defects is a core problem in bone tissue engineering. While minor bone defects can self-repair if the periosteum remains intact and normal osteogenesis occurs, significant defects or conditions such as congenital osteogenesis imperfecta present substantial challenges to self-healing. As research on mesenchymal stem cell (MSC) advances, new fields of application have emerged; however, their application in orthopedics remains one of the most established and clinically valuable directions. This review aims to provide a comprehensive overview of the research progress regarding MSCs in the treatment of diverse bone defects. MSCs, as multipotent stem cells, offer significant advantages due to their immunomodulatory properties and ability to undergo osteogenic differentiation. The review will encompass the characteristics of MSCs within the osteogenic microenvironment and summarize the research progress of MSCs in different types of bone defects, ranging from their fundamental characteristics and animal studies to clinical applications.

Ilizarov Distraction for Congenital Pseudoarthrosis of the Tibia in Adults

OBJECTIVE

The clinical evidence on the management for congenital pseudoarthrosis of the tibia (CPT) in adults is limited. The aim of this study is to assess the functional and radiological outcomes of Ilizarov distraction for treating CPT in adults.

METHODS

A retrospective analysis was conducted. Between 2013 and 2022, an Ilizarov distraction technique was performed on 14 adults (14 limbs) with CPT in our limb deformity center. There were seven females and seven males with a mean age of 33.7 (range, 18 ~ 53) years. The diagnosis of NF-1 was confirmed in seven (50.0%) patients. Eight patients had a history of previous surgical failure. The pseudoarthrosis occurred in the middle and lower tibia in all limbs (six left and eight right). The CPT was classified by Crawford classification and Paley classification. The surgical procedures, external fixation time (EFT), and all outcomes and complications were recorded. The Kolmogorov-Smirnov test was performed to test the normality of the data. The American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score at the preoperative and final follow-up was compared by using the Wilcoxon's signed-rank test. The limb-length discrepancy (LLD) and a self-made exercise capacity score at the preoperative and final follow-up were compared by using the student's t-test. The clinical and radiological outcomes were assessed by the Inan scale.

RESULTS

The mean EFT of Ilizarov fixator was 19.5 months (range, 7.3 ~ 39.1). At a median follow-up of 26.8 months (IQR, 20.2 ~ 34.3), bone union of the pseudarthrosis and consolidation of the distraction zone were achieved in all patients. The mean LLD was decreased from 11.3 cm (range, 3.4 ~ 17.3) preoperatively to 1.1 cm (range, 0.3 ~ 3.7) (p < 0.05). The mean or median AOFAS ankle-hindfoot score was improved from 53.5 (IQR, 26.5 ~ 60.5) preoperatively to 63.9 (range, 53 to 73) at final follow-up (p < 0.05). The mean score for exercise capacity were improved from 4.9 (range, 1 to 8) preoperatively to 9.6 (range, 7 ~ 12) at final follow-up (p < 0.05). According to the criteria described by Inan et al., the clinical results were classified as good in 10 and fair in 4, while the radiological results were classified as excellent in three, good in 8, and fair in 2. The success rate was 92.9%, as refracture was defined as treatment failure and occurred in one patient.

CONCLUSION

Ilizarov distraction provided a suitable treatment option for the CPT in adults, as it could achieve a high rate of bone union, a good correction of secondary deformity, a low risk of refracture, and consequently restore a relatively functional limb.

Circ_0000888 regulates osteogenic differentiation of periosteal mesenchymal stem cells in congenital pseudarthrosis of the tibia

Congenital pseudarthrosis of the tibia (CPT) is a refractory condition characterized by the decreased osteogenic ability in tibial pseudarthrosis repair. Periosteal mesenchymal stem cells (PMSCs) are multipotent cells involved in bone formation regulation. However, the mechanisms underlying its role in CPT remain unclear. In this study, we observed downregulation of circ_0000888 and pleiotrophin (PTN), as well as upregulation of miR-338-3p in CPT derived PMSCs (CPT-dPMSCs). Our results demonstrated that circ_0000888 and PTN likely enhanced the viability, proliferation, and osteogenic ability of PMSCs, while miR-338-3p had the opposite effect. Further analysis confirmed the regulatory relationship circ_0000888 suppressed the activity of miR-338-3p and upregulated the expression of its downstream target PTN by binding to miR-338-3p, consequently promoting the viability and osteogenic differentiation ability of CPT-dPMSCs. Our findings unveil an unexpected link between circ_0000888/miR-338-3p/PTN in promoting osteogenic ability and indicate the potential pathogenic mechanisms of CPT.

Differential expression and effect analysis of lncRNA-mRNA in congenital pseudarthrosis of the tibia

Background: To analyze the lncRNA-mRNA differential expression and co-expression network of periosteal stem cells (PSCs) from congenital pseudarthrosis of the tibia (CPT) and normal patients, and to explore the role of key lncRNAs. Methods: Differentially expressed lncRNAs and mRNAs in PSCs were obtained by sequencing, and biological functions of differentially expressed mRNAs were detected by gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG) pathway and protein -protein interaction (PPI) analysis. The co-expression network of lncRNA-mRNA was constructed by correlation analysis of differentially expressed lncRNAs and mRNAs, and the key lncRNAs were screened according to the connectivity degree. After that, the cis-regulated target genes of differential expressed lncRNAs and mRNAs were predicted. Results: A total of 194 differentially expressed lncRNAs were identified, including 73 upregulated and 121 downregulated genes. A total of 822 differentially expressed mRNAs were identified, including 311 upregulated and 511 downregulated genes. GO, KEGG and PPI enrichment analysis showed that the regulatory function of differentially expressed mRNAs were mainly gathered in skeletal system development and tissue morphogenesis. The co-expression network with 226 nodes and 3,390 edges was constructed based on correlation analysis. A total of 10 key lncRNAs, including FAM227B, POM121L9P, AF165147 and AC103702, were screened according to connectivity degree. Prediction of target genes indicated that FAM227B-FGF7 and AC103702-HOXB4/5/6 may play an important role in the pathogenesis of CPT. Conclusion: A total of 10 key lncRNAs, including FAM227B, POM121L9P, AF165147, and AC103702, occupy the core position in the co-expression network, suggesting that these lncRNAs and their target genes may play an important role in the pathogenesis of CPT.

miR-30a inhibits the osteogenic differentiation of the tibia-derived MSCs in congenital pseudarthrosis via targeting HOXD8

Background

Congenital pseudarthrosis of the tibia (CPT) is an uncommon congenital deformity and a special subtype of bone nonunion. The lower ability of osteogenic differentiation in CPT-derived mesenchymal stem cells (MSCs) could result in progression of CPT, and miR-30a could inhibit osteogenic differentiation. However, the role of miR-30a in CPT-derived MSCs remains unclear.

Methods

The osteogenic differentiation of CPT-derived MSCs treated with the miR-30a inhibitor was tested by Alizarin Red S staining and alkaline phosphatase (ALP) activity. The expression levels of protein and mRNA were assessed by Western blot or quantitative reverse transcription-polymerase chain reaction (RT-qPCR), respectively. The interplay between miR-30a and HOXD8 was investigated by a dual-luciferase reporter assay. Chromatin immunoprecipitation (ChIP) was conducted to assess the binding relationship between HOXD8 and RUNX2 promoter.

Results

CPT-derived MSCs showed a lower ability of osteogenic differentiation than normal MSCs. miR-30a increased in CPT-derived MSCs, and miR-30a downregulation promoted the osteogenic differentiation of CPT-derived MSCs. Meanwhile, HOXD8 is a direct target for miR-30a, and HOXD8 could transcriptionally activate RUNX2. In addition, miR-30a could inhibit the osteogenic differentiation of CPT-derived MSCs by negatively regulating HOXD8.

Conclusion

miR-30a inhibits the osteogenic differentiation of CPT-derived MSCs by targeting HOXD8. Thus, this study might supply a novel strategy against CPT.

Clinical characteristics and in silico analysis of congenital pseudarthrosis of the tibia combined with neurofibromatosis type 1 caused by a novel NF1 mutation

Congenital pseudarthrosis of the tibia (CPT) is a rare congenital bone malformation, which has a strong relationship with Neurofibromatosis type 1 (NF1). NF1 is an autosomal dominant disease leading to multisystem disorders. Here, we presented the genotypic and phenotypic characteristics of one unique case of a five-generation Chinese family. The proband was CPT accompanied with NF1 due to NF1 mutation. The proband developed severe early-onset CPT combined with NF1 after birth. Appearance photos and X-ray images of the left limb of the proband showed significant bone malformation. Slit-lamp examination showed Lisch nodules in both eyes of the proband. Whole-exome sequencing (WES) and Sanger sequencing confirmed the truncation variant of NF1 (c.871G>T, p. E291^*). Sequence conservative and evolutionary conservation analysis indicated that the novel mutation (p.E291^*) was highly conserved. The truncated mutation led to the loss of functional domains, including CSRD, GRD, TBD, SEC14-PH, CTD, and NLS. It may explain why the mutation led to a severe clinical feature. Our report expands the genotypic spectrum of NF1 mutations and the phenotypic spectrum of CPT combined with NF1.

Novel method for the treatment of congenital pseudarthrosis of the tibia using the gastrocnemius flap: A preliminary study

PURPOSE

Congenital pseudarthrosis of the tibia is a rare disease that is particularly difficult to treat; the most difficult complications include nonunion of the tibia, refracture, and failed surgery. This study aimed to evaluate the efficiency of transposing gastrocnemius flaps for the treatment of congenital pseudarthrosis of the tibia.

METHODS

Nine patients (aged 6.2 ± 3.6 years) diagnosed with congenital pseudarthrosis of the tibia in our hospital between March 2013 and March 2018 were enrolled. The tibial pseudarthrosis and thickened periosteum were completely removed, and intramedullary nails were used to fix the tibia. Bone harvest from the iliac, mixed with allogenic bone, was filled in the gap created by excision of the pseudarthrosis site and the surrounding periosteum; the gastrocnemius flap was then used to wrap the pseudoarthrosis site. The plaster cast was fixed postoperatively. The tibial union was evaluated via radiograph, and the plaster cast was removed after 12-24 weeks. Patients began walking approximately 12-14 weeks postoperatively.

RESULTS

Anatomical reduction was achieved in all the patients; the mean bone healing time was 10.1 ± 2.1 months. Bone nonunion was observed in one patient, and no neurovascular injury or wound infection occurred. Limb length discrepancy was in the range 3.2 ± 1.8 cm at 1 year and 4.7 ± 2.7 cm at 2 years after surgery. Two patients underwent replacement of the intramedullary nail, and eight patients exhibited good functional and radiographic outcomes.

CONCLUSION

This preliminary study proved that using the gastrocnemius muscle flap to cover the pseudarthrosis site was an effective method to promote the tibial union and treat congenital pseudarthrosis of the tibia.

Serum-derived exosomes from neurofibromatosis type 1 congenital tibial pseudarthrosis impaired bone by promoting osteoclastogenesis and inhibiting osteogenesis

Treatment of congenital pseudarthrosis of the tibia (CPT) still is full of challenges in pediatric orthopedist. Serum-derived exosomes (SDEs) have been proven to be participated in bone remodeling. However, the molecular changes in SDEs of CPT children and their pathologies have not been elucidated. In this study, SDEs were isolated and purified from CPT patients (CPT-SDEs) associated with neurofibromatosis type 1 (NF1) and normal children (Norm-SDEs). Then we obtained the proteomics profile of SDEs by combining liquid chromatography-tandem mass spectrometry (LC-MS/MS) and tandem mass tag label-based quantitation. In vitro, the efficacy of SDEs on osteoblastic differentiation of MC3T3-E1 cells and osteoclastogenesis ability of RAW264.7 cells were evaluated by quantitative real-time PCR (qRT-PCR) and cytochemical staining. In vivo, we used micro-CT to assess cortical bone mass and trabecular microstructures to reflect the influence of SDEs on bone remodeling after injection into the tail vein of rats. Based on proteomics analysis, 410 differentially expressed proteins, including 289 downregulated proteins and 121 upregulated proteins, were identified in the CPT-SDEs. These proteins have multiple biological functions associated with cellular metabolic processes, catalytic activity, and protein binding, which are important for cell differentiation and proliferation. In vitro, CPT-SDEs decreased the osteogenic differentiation of MC3T3-E1 cells and promoted the osteoclastogenesis of RAW264.7 cells. Injection of CPT-SDEs into the tail vein for two months resulted in bone loss in rats, as indicated by the decrease in trabecular and cortical bone mass. Our findings demonstrated the differences in proteins in SDEs between normal and CPT children with NF1. These differentially expressed proteins in CPT-SDEs contributed to deteriorating trabecular bone microstructures by inhibiting bone formation and stimulating bone resorption.

Outcome of Induced Membrane Technique in Treatment of failed previously operated Congenital Pseudarthrosis of the Tibia

BACKGROUND

Although a remarkable success in the treatment of congenital pseudarthrosis tibia (CPT) had been achieved, failure rate is still high and the likelihood of amputation is still considerable. The current study evaluates the outcome of induced membrane technique in the treatment of failed previously operated patients of congenital pseudarthrosis of the tibia. We hypothesized that induced membrane technique will improve union rates in CPT with failed previous multiple operations.

PATIENTS AND METHODS

Nineteen consecutive patients of failed previously operated CPT were prospectively included in the study. All patients were treated by induced membrane technique with autogenous free non-vascularized fibular strut graft augmented by autogenous iliac graft and fixed by intramedullary K-Wire as well as Ilizarov external fixator.

RESULTS

The mean interval between the 1^st and 2^nd stages of the procedure was 4.9 weeks. Sound union was achieved in all cases in a mean time of 25.3 weeks. The mean follow up period was 5.02 years (range, 2.4-6.5). No refracture was documented till last follow up.

CONCLUSION

Induced membrane technique had proved as a successful method in the treatment of failed previously operated CPT with a satisfactory outcome and low complication rates.

LEVEL OF EVIDENCE

IV.

Identification and characterization of NF1 and non-NF1 congenital pseudarthrosis of the tibia based on germline NF1 variants: genetic and clinical analysis of 75 patients

Background

Congenital pseudarthrosis of the tibia (CPT) is a rare disease. Some patients present neurofibromatosis type 1 (NF1), while some others do not manifest NF1 (non-NF1). The etiology of CPT, particularly non-NF1 CPT, is not well understood. Here we screened germline variants of 75 CPT cases, including 55 NF1 and 20 non-NF1. Clinical data were classified and analyzed based on NF1 gene variations to investigate the genotype-phenotype relations of the two types of patients.

Results

Using whole-exome sequencing and Multiplex Ligation-Dependent Probe Amplification, 44 out of 55 NF1 CPT patients (80.0%) were identified as carrying pathogenic variants of the NF1 gene. Twenty-five variants were novel; 53.5% of variants were de novo, and a higher proportion of their carriers presented bone fractures compared to inherited variant carriers. No NF1 pathogenic variants were found in all 20 non-NF1 patients. Clinical features comparing NF1 CPT to non-NF1 CPT did not show significant differences in bowing or fracture onset, lateralization, tissue pathogenical results, abnormality of the proximal tibial epiphysis, and follow-up tibial union after surgery. A considerably higher proportion of non-NF1 patients have cystic lesion (Crawford type III) and used braces after surgery.

Conclusions

We analyzed a large cohort of non-NF1 and NF1 CPT patients and provided a new perspective for genotype-phenotype features related to germline NF1 variants. Non-NF1 CPT in general had similar clinical features of the tibia as NF1 CPT. Germline NF1 pathogenic variants could differentiate NF1 from non-NF1 CPT but could not explain the CPT heterogeneity of NF1 patients. Our results suggested that non-NF1 CPT was probably not caused by germline NF1 pathogenic variants. In addition to NF1, other genetic variants could also contribute to CPT pathogenesis. Our findings would facilitate the interpretation of NF1 pathogenic variants in CPT genetic counseling.

Supplementary information

The online version of this article (10.1186/s13023-019-1196-0) contains supplementary material, which is available to authorized users.

Evaluation of bone marrow-derived mesenchymal stem cell quality from patients with congenital pseudoarthrosis of the tibia

Background

The treatment of congenital pseudoarthrosis of the tibia (CPT) remains challenging in pediatric orthopedics due to the difficulties in bone union, continuous angulation, joint stiffness, and severe limb length discrepancy. Mesenchymal stem cells (MSCs) therapy offers a complementary approach to improve the conventional surgical treatments. Although the autologous MSC treatment shows a promising strategy to promote bone healing in CPT patients, the quality of MSCs from CPT patients has not been well studied. The purpose of this study is to investigate the quality of MSCs isolated from patients with CPT.

Methods

The bone marrow-derived MSCs from the fracture site and iliac crest of six CPT patients were isolated and compared. The cumulative population doubling level (cPDL), phenotype characteristics, and trilineage differentiation potency were observed to assess the quality of both MSCs.

Results

There were no significant differences of the MSCs derived from the fracture site and the MSCs from the iliac crest of the subjects, in terms of cPDL, phenotype characteristics, and trilineage differentiation potency (all p > 0.05). However, MSCs from the fracture site had a higher senescence tendency than those from the iliac crest.

Conclusion

MSC quality is not the main reason for delayed bone regeneration in those with CPT. Thus, autologous MSC is a promising source for treating CPT patients

Wrapping grafting for congenital pseudarthrosis of the tibia: A preliminary report

OBJECTIVE

Treatment of congenital pseudarthrosis of the tibia (CPT) remains a challenge. The autogenic iliac bone graft is important consistent of treatment for CPT. The purpose of this study was to investigate the role of wrapping autogenic iliac bone graft in improvement of the curing opportunities of CPT.

METHODS

We combined Ilizarov fixator with intramedullary rodding of the tibia and wrapping autogenic iliac bone graft for treatment 51 cases of CPT between 2007 and 2010. The mean age is 3.2 years at index operation, of which 31 patients (61%) were below 3 years old. According to Crawford classification, 5 tibia had type-II morphology; 3, type-III; 43, type-IV.

RESULTS

In the postoperative follow-up of 3.5 months (range from 3 to 4.5 months), all cases were found that the bone graft sites of pseudarthrosis of the tibia showed a significant augmentation and spindle-shaped expansion as obvious change. All cases of this series have been followed-up, average followed-up time were 1.6 years (range from 7 to 3.1 years), of which 19 cases were more than 2 years. The average time of removed the Ilizarov ring fixator was 3.5 months (range from 3 to 4.5 months). According to Johnston Clinical evaluation system, 26 cases had grade I, 21 cases, grade II, 4 cases, grade III. Following the Ohnishi X-ray evaluation criteria, union of pseudarthrosis of the tibia were 42 cases, delayed union 5 cases, nonunion 4 cases.

CONCLUSION

Autogenic iliac bone graft is able to offer the activity of osteoblasts and osteogenesis induced by bone morphogenetic protein (BMP) and glycoprotein, meanwhile enclosing bone graft could help keep cancellous bone fragments in close contact around pseudarthrosis of the tibia, allowing the formation of high concentration of glycoprotein and BMP induced by chemical factors because of established the sealing environment in location, all of which could enhance the healing of pseudarthrosis of the tibia.

Hybrid composites of mesenchymal stem cell sheets, hydroxyapatite, and platelet-rich fibrin granules for bone regeneration in a rabbit calvarial critical-size defect model

The reconstruction of large bone defects remains a major clinical challenge, and tissue engineering is a promising technique for resolving this problem. Many attempts have been made to optimize bone tissue engineering protocols. The aim of the present study was to develop a process incorporating mesenchymal stem cell (MSC) sheets with nanoscale hydroxyapatite (nano-HA) and autologous platelet-rich fibrin (PRF) granules for enhanced bone formation within a critical-sized rabbit cranial defect. MSC sheets and PRF were prepared prior to in vivo experiments. The osteogenic differentiation ability of MSCs and the ultrastructure of PRF were also studied. A total of 15 New Zealand white rabbits were used in the current study and critical-size defects (CSDs) were surgically introduced in the cranium (diameter, 15 mm). The surgical defects were treated with MSC/PRF composites, MSC composites or left empty. Animals were euthanized at week 8 post-surgery. Iconography, histological and histomorphometric analysis were performed to assess de novo bone formation. The percentage of new bone in the MSC/PRF group (35.7±5.1%) was significantly higher than that in the MSC (18.3±3.2%; P<0.05) and empty defect groups (4.7±1.5%; P<0.05). The results of the present study suggest that combined application of an MSC sheet with nano-HA and granular PRF enhances bone regeneration in a rabbit calvarial CSD model, and provides a novel insight into bone tissue regeneration for large bone defects.

Congenital pseudarthrosis of the clavicle: a report on 27 cases

HYPOTHESIS

We aimed to report our experience in treating congenital pseudarthrosis of the clavicle (CPC).

MATERIALS AND METHODS

A retrospective search of the archive of our institute was performed; 27 cases (12 male and 15 female patients) affected by CPC were recorded. Among these patients, 19 underwent surgical intervention for cosmetic appearance between 1960 and 2015. Of 19 patients, 18 were treated by pseudarthrosis resection and stabilization with a Kirschner wire, whereas in 1 case, the osteosynthesis was performed with a plate. Iliac crest bone autograft was used in 15 patients, whereas 4 patients were treated with a fibular allograft.

RESULTS

The mean follow-up period was 36.3 ± 49.1 months. Bone healing was achieved in 14 of 19 operated cases (74%); none of the patients had complaints regarding cosmetic abnormalities or unesthetic appearance. All the operated patients were pain free, range of motion was complete, and no other subjective anomalies were found. No vascular or neurologic complications were observed. However, the use of allograft was associated with high rates of nonunion in this case series (P = .037).

CONCLUSION

CPC can be satisfactorily treated by K-wire fixation and autologous iliac crest bone grafting, which showed better results in terms of functional and cosmetic outcome.

Delayed presentation of congenital tibial pseudarthrosis and neurofibromatosis: a difficult union

Background: A new case of congenital pseudarthrosis of the tibia (CPT) presents yearly to CSC, but treatment is prolonged, and not always successful.

Objective: To study the outcomes of treatment, and to determine whether a relationship with neurofibromatosis (NF) was of significance.

Methods: A review of the medical records at our centre revealed 11 cases of CPT, 5 of which were associated with neurofibromatosis.

Results: Most patients had multiple operations for their case of CPT, which did finally lead to union in 6 out of 6 cases with no NF, but in only 1 case out of 5 when NF was present.

Conclusion: Late presentation and severe deformity can be overcome, and union can be achieved, but NF has a deleterious effect on obtaining union.

Refixation, allograft and adjuvant cell therapy to treat nonunion of the femoral neck in a child

INTRODUCTION

Idiopathic posttraumatic nonunion is a rare condition in children; the treatment of this complication is still controversial in this peculiar population.

CASE REPORT

We report a case of a subcapital type II femoral neck fracture, in a 12-year-old boy, which was initially treated by internal fixation and subsequently went on to a nonunion at the femoral neck, in absence of infection or other disease.1 year after index surgery we performed surgical debridement and refixation with plate and bone allograft, added with autologous bone marrow aspiration concentrate (BMAC) and platelet-rich fibrin (PRF).After 3 months the nonunion healed and the boy was allowed full weight-bearing.

CONCLUSIONS

Combined surgery and adjuvant cell therapy can be considered an option of treatment in nonunion of the femoral neck in the paediatric population.

Does pamidronate enhance the osteogenesis in mesenchymal stem cells derived from fibrous hamartoma in congenital pseudarthrosis of the tibia?

Neurofibromatosis type 1 (NF1) is a commonly occurring genetic disorder in children. Mutation in the NF1 gene has its implication in poor osteoblastic capabilities. We hypothesised that pamidronate will enhance the osteoblastic potential of the mesenchymal stem cells (MSCs) derived from lipofibromatosis tissue of children with congenital pseudarthrosis tibia (CPT) associated with NF1. In this study, bone marrow MSCs (BM MSCs) and CPT MSCs were obtained from three patients undergoing salvage surgeries/bone grafting (healthy controls) and those undergoing excision of the hamartoma and corrective surgeries respectively. The effects of pamidronate (0, 10 nM, 100 nM and 1 μM) on cell proliferation, toxicity and differentiation potential were assessed and the outcome was measured by staining and gene expression. Our outcome showed that CPT MSCs had more proliferation rate as compared to BM MSCs. All 3 doses of pamidronate did not cause any toxicity to the cells in both the groups. The CPT MSCs showed less differentiation with pamidronate compared to the healthy control MSCs. This was quantitated by staining and gene expression analysis. Therefore, supplementation with pamidronate alone will not aid in bone formation in patients diagnosed with CPT. An additional stimulus is required to enhance bone formation.

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First study demonstrating the differentiation potential of MSCs derived from the hamartoma using pamidronate

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The CPT MSCs have lower osteogenic potential as compared to BM MSCs.

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The osteoblastic response does not improve with the addition of pamidronate (1 μM) in CPT MSCs.

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Pamidronate enhances osteogenic differentiation in normal BM MSCs.

Management of congenital pseudarthrosis of the tibia with the Ilizarov method in a paediatric population: influence of aetiological factors

PURPOSE

Our study compared the rates of union achieved with the Ilizarov method in congenital pseudarthrosis of the tibia (CPT) associated with neurofibromatosis type 1 (NF1) or CPT of idiopathic origin in paediatric patients.

METHODS

We studied the outcomes of 28 children that were treated for CPT between 2005 and 2013. Group 1 included children (n = 14, mean age = 9.7 years) with CPT associated with NF1 while group 2 were CPT cases that had radiographic confirmation of dysplastic lesions in the tibia but lacked clinical NF1 manifestations (n = 14, mean age = 8.6 years). There was no statistical difference between the groups regarding their age or number of previous operations per patient. Individual technical solutions were planned for each patient but coaptation of bone fragments and autologous local tissue grafting to achieve a greater bone thickness and contact area at the pseudarthrosis level were mainly used. Refracture-free rate after the first operation, number of re-operations per patient, and union rates in the groups were compared.

RESULTS

Bone union and weight bearing were obtained in all the cases after the first operation. Refracture-free rate was 42.86 % in group 1 and 35.71% in group 2 (no statistical difference, p > 0.05). Mean number of re-operations per patient was 1.07 and 0.78 respectively (p > 0.05). Subsequent treatment for refractures with the Ilizarov techniques gained 92.86% of union in both groups at the follow-ups by completion of the study (range, 2-9 years).

CONCLUSIONS

The Ilizarov method yields comparable results in the management of CPT associated with NF1 or tibial dysplasia of idiopathic origin in paediatric cases. Further research should focus on the ways to support the Ilizarov method in order to reduce the number of repetitive surgeries or eliminate them.

Preparation method and growth factor content of platelet concentrate influence the osteogenic differentiation of bone marrow stromal cells

BACKGROUND AIMS

An extensive debate about the clinical benefits of autologous platelet concentrates used as a treatment option for patients with orthopedic injuries is ongoing. The aim of this study was to determine whether different compositions of platelet concentrates may affect the osteogenic differentiation of bone marrow stromal cells (BMSC).

METHODS

Pure platelet-rich plasma (P-PRP) and leukocyte-PRP (L-PRP) were characterized for platelet and leukocyte content. As an indicative marker of the delivery of growth factors (GFs), the release of basic fibroblast growth factor (bFGF) from platelet gel (PG) was measured at 1, 18, 48 and 72 h and at 7 d. The ability of different PGs to induce proliferation and differentiation of BMSC was evaluated by using bioactivity assays.

RESULTS

The platelet recovery was significantly higher in L-PRP, either fresh or frozen. PGs derived from L-PRP and P-PRP showed significant differences in terms of bFGF release and biological activity. bFGF release was faster both in fresh and frozen L-PRP preparations. Moreover, L-PRP samples were able to induce a significantly higher proliferation of BMSC compared with P-PRP or PPP samples. Even though all PG preparations allowed the deposition of mineral nodules in BMSC cultures, the mineralization activity correlated significantly with bFGF levels.

CONCLUSIONS

The biological activity of platelet concentrates differs according to preparation technique, which affects platelet and leukocyte content and GF availability. Because GF levels are not always optimal in subjects with defective bone healing, composition and bioactivity of PRP should be analyzed to test the reliability and potential effectiveness of the regenerative treatment.

New insights into osteogenic and chondrogenic differentiation of human bone marrow mesenchymal stem cells and their potential clinical applications for bone regeneration in pediatric orthopaedics

Human mesenchymal stem cells (hMSCs) are pluripotent adult stem cells capable of being differentiated into osteoblasts, adipocytes, and chondrocytes. The osteogenic differentiation of hMSCs is regulated either by systemic hormones or by local growth factors able to induce specific intracellular signal pathways that modify the expression and activity of several transcription factors. Runt-related transcription factor 2 (Runx2) and Wnt signaling-related molecules are the major factors critically involved in the osteogenic differentiation process by hMSCs, and SRY-related high-mobility-group (HMG) box transcription factor 9 (SOX9) is involved in the chondrogenic one. hMSCs have generated a great interest in the field of regenerative medicine, particularly in bone regeneration. In this paper, we focused our attention on the molecular mechanisms involved in osteogenic and chondrogenic differentiation of hMSC, and the potential clinical use of hMSCs in osteoarticular pediatric disease characterized by fracture nonunion and pseudarthrosis.

Improved hypothermic short-term storage of isolated mouse islets by adding serum to preservation solutions

Preserving isolated islets at low temperature appears attractive because it can keep islet quantity comparable to freshly isolated islets. In this study, we evaluated the effect of serum as an additive to preservation solutions on islet quality after short-term hypothermic storage. Isolated mouse islets were preserved at 4°C in University of Wisconsin solution (UW) alone, UW with serum, M-Kyoto solution (MK) alone or MK with serum. We then assessed islet quantity, morphology, viability and function in vitro as well as in vivo. Islet quantity after storage in all four solutions was well maintained for up to 120 h. However, islets functioned for different duration; glucose-stimulated insulin release assay revealed that the duration was 72 h when islets were stored in UW with serum and MK with serum, but only 24 h in UW alone, and the islet function disappeared immediately in MK alone. Viability assay confirmed that more than 70% islet cells survived for up to 48 h when islets are preserved in UW with serum and MK with serum, but the viability decreased rapidly in UW alone and MK alone. In in vivo bioassays using 48-h preserved isogeneic islets, all recipient mice restored normal blood glucose concentrations by transplants preserved in UW with serum or MK with serum, whereas 33.3% recipients and no recipient restored diabetes by transplants preserved in UW alone and in MK alone respectively. Adding serum to both UW and MK improves their capability to store isolated islets by maintaining islet functional viability.