Peripheral blood stem cell transplantation for ischemic femoral head necrosis

Steroid-Induced Osteonecrosis of the Femoral Head: Novel Insight Into the Roles of Bone Endothelial Cells in Pathogenesis and Treatment

Steroid-induced osteonecrosis of the femoral head (SONFH) is a disease characterized by the collapse of the femoral head. SONFH occurs due to the overuse of glucocorticoids (GCs) in patients with immune-related diseases. Among various pathogenesis proposed, the mechanism related to impaired blood vessels is gradually becoming the most convincing hypothesis. Bone endothelial cells including bone microvascular endothelial cells (BMECs) and endothelial progenitor cells (EPCs) play a crucial role in the maintenance of vascular homeostasis. Therefore, bone endothelial cells are key regulators in the occurrence and progression of SONFH. Impaired angiogenesis, abnormal apoptosis, thrombosis and fat embolism caused by the dysfunctions of bone endothelial cells are considered to be the pathogenesis of SONFH. In addition, even with high disability rates, SONFH lacks effective therapeutic approach. Icariin (ICA, a flavonoid extracted from Epimedii Herba), pravastatin, and VO-OHpic (a potent inhibitor of PTEN) are candidate reagents to prevent and treat SONFH through improving above pathological processes. However, these reagents are still in the preclinical stage and will not be widely used temporarily. In this case, bone tissue engineering represented by co-transplantation of bone endothelial cells and bone marrow mesenchymal stem cells (BMSCs) may be another feasible therapeutic strategy.

Tissue Engineering Strategies for Treating Avascular Necrosis of the Femoral Head

Avascular necrosis (AVN) of the femoral head commonly leads to symptomatic osteoarthritis of the hip. In older patients, hip replacement is a viable option that restores the hip biomechanics and improves pain but in pediatric, adolescent, and young adult patients hip replacements impose significant activity limitations and the need for multiple revision surgeries with increasing risk of complication. Early detection of AVN requires a high level of suspicion as diagnostic techniques such as X-rays are not sensitive in the early stages of the disease. There are multiple etiologies that can lead to this disease. In the pediatric and adolescent population, trauma is a commonly recognized cause of AVN. The understanding of the pathophysiology of the disease is limited, adding to the challenge of devising a clinically effective treatment strategy. Surgical techniques to prevent progression of the disease and avoid total hip replacement include core decompression, vascular grafts, and use of bone-marrow derived stem cells with or without adjuncts, such as bisphosphonates and bone morphogenetic protein (BMP), all of which are partially effective only in the very early stages of the disease. Further, these strategies often only improve pain and range of motion in the short-term in some patients and do not predictably prevent progression of the disease. Tissue engineering strategies with the combined use of biomaterials, stem cells and growth factors offer a potential strategy to avoid metallic implants and surgery. Structural, bioactive biomaterial platforms could help in stabilizing the femoral head while inducing osteogenic differentiation to regenerate bone and provide angiogenic cues to concomitantly recover vasculature in the femoral head. Moreover, injectable systems that can be delivered using a minimal invasive procedure and provide mechanical support the collapsing femoral head could potentially alleviate the need for surgical interventions in the future. The present review describes the limitations of existing surgical methods and the recent advances in tissue engineering that are leading in the direction of a clinically effective, translational solution for AVN in future.

Stem cell therapy for osteonecrosis of femoral head: Opportunities and challenges

Osteonecrosis of the femoral head (ONFH) is a progressive disease with a complex etiology and unclear pathogenesis, resulting in severe hip pain and dysfunction mainly observed in young patients. Although total hip arthroplasty (THA) is the most effective treatment for patients with ONFH in the terminal stage, the results of THA in young patients or active populations are often not favorable, with some complications related to the prosthesis. With the development of biotechnology, an increasing number of studies pay attention to use of stem cells for the treatment of ONFH. Stem cells are characterized by the ability to self-renew and differentiate into multiple cell types, including differentiation into osteoblasts and endothelial cells to mediate bone repair and angiogenesis. Furthermore, stem cells can offer growth factors to promote blood supply in the necrotic regions by paracrine effects. Therefore, stem cell therapy has become one of the hip-preserving alternatives for ONFH. This review summarized the current trends in stem cell therapy for ONFH, from clinical applications to related basic research, and showed that an increasing number of studies have confirmed the effectiveness of stem cell therapy in ONFH. However, many unsolved problems and challenges in practical applications of stem cell therapy still exist, such as patient selection, standardized procedures, safety assessment, and the fate of transplanted cells in the body. Additional studies are required to find ideal cell sources, appropriate transplantation methods, and the optimal number of cells for transplantation.

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Diversities in repair processes present a challenge in the targeted treatment of ONFH.

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Osteogenesis and angiogenesis are the primary mechanisms of MSCs treatment in ONFH.

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Systematic safety assessment and cell tracing are necessary for stem cell therapy.

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Optimal numbers and methods of cell transplantation need to be further confirmed.

Prognosis after autologous peripheral blood stem cell transplantation for osteonecrosis of the femoral head in the pre-collapse stage: a retrospective cohort study

OBJECTIVES

Autologous peripheral blood stem cell (auto-PBSC) transplantation is an effective therapeutic for the osteonecrosis of the femoral head (ONFH) but without prognosis estimation. This study mainly aimed to (1) determine whether auto-PBSC transplantation is a promising option, (2) assess the risk of hip-preservation failure, (3) achieve a predictive model of femoral head survival after the intervention, and (4) eventually identify clinical indications for auto-PBSC transplantation in future.

METHODS

After reviewing the in-patient database of the First Affiliated Hospital of Zhejiang Chinese Medicine University from June 2012 to June 2014, 37 eligible patients with Association Research Circulation Osseous stage I or II ONFH who were receiving intra-arterial infusion of auto-PBSCs were recruited. A case form was designed to retrieve relevant data. Hip-preservation failure was defined as the endpoint. All participants were stratified by the categorical risk of collapse, which was statistically tested through log-rank analysis. All significant factors were evaluated using Cox proportional hazards regression model, and a predictive nomogram plot was generated.

RESULTS

In total, 47 hips were followed up for 53.96 ± 21.09 months; the median survival time was 60.18 months. Among the predictors, body mass index (BMI; P = 0.0015) and Harris hip score (HHS; P < 0.0001) independently affected femoral head survival. Patients with BMI ≥ 24 kg/m² exhibited a 2.58 times higher risk of hip-preservation failure [95% confidence interval (CI), 1.32-5.45] than those with BMI < 24 kg/m², whereas those with HHS ≥ 70 exhibited a 0.19 times lower risk (95% CI, 0.09-0.38) than those with HHS < 70. Hazard ratios associated with age (P = 0.042), BMI (P = 0.012), HHS (P = 0.022), and necrotic volume (P = 0.000) were 1.038 (95% CI, 1.001-1.075), 1.379 (95% CI, 1.072-1.773), 0.961 (95% CI, 0.928-0.994), and 1.258 (95% CI, 1.120-1.412), respectively. A nomogram plot (score test P = 0.000; C-index = 0.8863) was available for the orthopedic doctor to predict hip survival probability.

CONCLUSIONS

The results suggest that intra-arterial infusion of auto-PBSCs prolongs femoral head survival. Age, BMI, HHS, and necrotic volume can influence the efficacy of this intervention. This study was approved by ethics committee of the trial center, number 2019-KL-075-01.

OGR1 mediates the inhibitory effects of acidic environment on proliferation and angiogenesis of endothelial progenitor cells

Ovarian cancer G-protein-coupled receptor 1 (OGR1), an acid-sensitive receptor, plays a key proton-sensing role through stimulation of inositol phosphate formation. Avascular necrosis of the femoral head is characterized by apoptosis of bone cells mainly resulting from deficient local blood perfusion, eventually leading to acidification with disruption of endothelial progenitor cells' (EPCs) function. However, whether EPCs express OGR1 has not been demonstrated. This study attempted to whether OGR1 mediates the effects of acid on proliferation, migration, and angiogenesis in EPCs. FITC-UEA-I and Dil-Ac-LDL double-staining methods were used to identify EPCs. Expression of OGR1 was analyzed by RT-PCR (reverse transcription PCR) and western blot after incubation in media ranging in pH, cell counting kit-8 and cell cycle analysis were used to analyze proliferation and cell cycle distribution. Scratch test, transwell migration assay, and tube formation experiments were performed to analyze migration and vascularization of EPCs after silencing OGR1 with small interfering RNA (siRNA). The result show EPCs were positive for FITC-UEA-I and Dil-Ac-LDL double-staining and expressed OGR1. The expression of OGR1 increased gradually with decreased pH and was highest in pH 6.4 medium. Incubation in pH 6.4 medium inhibited proliferation of EPCs and caused cell cycle arrest. Silencing of OGR1 using siRNA partially reversed the effect of acidic environment on EPCs. Migration and angiogenesis of EPCs were inhibited in pH 6.4 medium, and silencing of OGR1 partially reversed this effect. The results demonstrated expression of OGR1 in EPCs, and the OGR1 mediated the effects of acidic environment on proliferation, migration, and angiogenesis of EPCs.

The physiopathology of avascular necrosis of the femoral head: an update

The physiopathology of the femoral head bone necrosis is similar for children and for adults. The disease is characterized by apoptosis of bone cells - bone marrow and bone forming cells-resulting in head collapse with a subsequent lesion of the overlying cartilage, and therefore flattening of the rounded surface shape of the head articulating with the acetabulum, provoking, eventually, secondary osteoarthritis. When the disease becomes clinically evident already destructive phenomena have occurred and collapse will eventually ensue. In children, because epiphyseal cartilage has growth capabilities, lost epiphyseal height can be recovered, however in adults collapse is irreversible. In this paper the physiopathology of this disease is examined as well as its implication for treatment. Prevention by genetic studies is discussed.

Combination treatment of biomechanical support and targeted intra-arterial infusion of peripheral blood stem cells mobilized by granulocyte-colony stimulating factor for the osteonecrosis of the femoral head: a randomized controlled clinical trial

The objective of this study was to determine the benefits of combination treatment with mechanical support and targeted intra-arterial infusion of peripheral blood stem cells (PBSCs) mobilized by granulocyte-colony stimulating factor (G-CSF) via the medial circumflex femoral artery on the progression of osteonecrosis of the femoral head (ONFH). Fifty-five patients (89 hips) with early and intermediate stage ONFH were recruited and randomly assigned to combination treatment or mechanical support treatment (control group). All hips received mechanical support treatment (porous tantalum rod implantation). Then, hips in the combination treatment group were performed targeted intra-arterial infusion of PBSCs. At each follow-up, Harris hip score (HHS) and Association Research Circulation Osseous (ARCO) classification were used to evaluate the symptoms and progression of osteonecrosis. Total hip arthroplasty (THA) was assessed as an endpoint at each follow-up. At 36 months, 9 of the 41 hips (21.95%) in the control group progressed to clinical failure and underwent THA whereas only 3 of the 48 hips (6.25%) in the combination treatment group required THA (p = 0.031). Kaplan-Meier survival analysis showed a significant difference in the survival time between the two groups (log-rank test; p = 0.025). Compared to the control group, combination treatment significantly improved the HHS at 36 months (p = 0.003). At the final follow-up examination, radiological progression was noted in 13 of 41 hips (31.71%) for the control group, but in only 4 of 48 hips (8.33%) for the combination treatment group (p = 0.005). The overall collapse rates were 15.15% (5/33 hips) and 8.11% (3/37 hips) in the control and combination treatment groups, respectively. Targeted intra-arterial infusion of PBSCs is capable of enhancing the efficacy of biomechanical support in the treatment of ONFH. This clinical trial confirmed that the combination treatment might be a safe and feasible choice for the treatment of early or intermediate stages of ONFH.

Stem cell therapy for the treatment of early stage avascular necrosis of the femoral head: a systematic review

Background

Avascular necrosis (AVN) of the femoral head (FH) is believed to be caused by a multitude of etiologic factors and is associated with significant morbidity in younger populations. Eventually, the disease progresses and results in FH collapse. Thus, a focus on early disease management aimed at joint preservation by preventing or delaying progression is key. The use of stem cells (SC) for the treatment of AVN of the FH has been proposed. We undertook a systematic review of the medical literature examining the use of SC for the treatment of early stage (precollapse) AVN of the FH, in both pre-clinical and clinical studies.

Methods

Data collected included: Pre-clinical studies – model of AVN, variety and dosage of SC, histologic and imaging analyses. Clinical studies – study design, classification and etiology of AVN, SC dosage and treatment protocol, incidence of disease progression, patient reported outcomes, volume of necrotic lesion and hip survivorship.

Results

In pre-clinical studies, the use of SC uniformly demonstrated improvements in osteogenesis and angiogenesis, yet source of implanted SC was variable. In clinical studies, groups treated with SC showed significant improvements in patient reported outcomes; however hip survivorship was not affected. Discrepancies regarding dose of SC, AVN etiology and disease severity were present.

Conclusions

Routine use of this treatment method will first require further research into dose and quality optimization as well as confirmed improvements in hip survivorship.

Osteonecrosis in children after allogeneic hematopoietic cell transplantation: study of prevalence, risk factors and longitudinal changes using MR imaging

Osteonecrosis after hematopoietic SCT (HCT) has seldom been addressed in pediatric populations. At our institution, since January 2002, children undergoing allogeneic HCT (alloHCT) receive yearly follow-up magnetic resonance imaging (MR) of hips and knees. To estimate the prevalence, longitudinal changes and associated risk factors for osteonecrosis after alloHCT, we reviewed MRs for children who underwent single alloHCT during the study period. We analyzed 149 of 344 patients who had post-HCT MR imaging performed (84 males; median age 11 years (range, 0.5-21 years)), median follow-up time was 32.6 months (range, 2.8-97.2 months). In all, 44 (29.5%) developed osteonecrosis of hips and/or knees; of those, 20 (45%) had at least 30% epiphyseal involvement. In 23 (52%), osteonecrosis lesions were identified in the first and in 43 (98%) by the third yearly scan. Knees were more frequently involved than hips; severity of osteonecrosis was greater in hips. Those who had pre-alloHCT osteonecrosis, two patients' hips and six patients' knees resolved completely; three patients' osteonecrosis lesions regressed after alloHCT. On risk factor analysis, age at time of alloHCT (P=0.051) and osteonecrosis identified by MRs before alloHCT (P=0.001) were the primary risk factors. This analysis shows that preventive strategies for osteonecrosis in this population should focus on measures to minimize risk factors before alloHCT.

Osteonecrosis in children after allogeneic hematopoietic cell transplantation: study of prevalence, risk factors and longitudinal changes using MR imaging

Osteonecrosis after hematopoietic stem cell transplantation (HCT) has seldom been addressed in pediatric populations. At our institution, since January 2002, children undergoing allogeneic HCT (alloHCT) receive yearly follow-up magnetic resonance imaging (MR) of hips and knees. To estimate the prevalence, longitudinal changes and associated risk factors for osteonecrosis after alloHCT, we reviewed MRs for children who underwent single alloHCT during the study period. We analyzed 149 of 344 patients who had post HCT MRI imaging performed [84 males; median age11 years (range, 0.5–21years)], median follow-up time was 32.6 months (range, 2.8–97.2 months). Forty-four (29.5%) developed osteonecrosis of hips and/or knees; of those, 20 (45%) had at least 30% epiphyseal involvement. In 23 (52%) osteonecrosis lesions were identified in the first, and 43 (98%) by the third yearly scan. Knees were more frequently involved than hips; severity of osteonecrosis was greater in hips. Those who had pre-alloHCT osteonecrosis, two patients’ hips and six patients’ knees resolved completely; three patients’ osteonecrosis lesions regressed after alloHCT. On risk factor analysis, age at time of alloHCT (p=0.051) and osteonecrosis identified by MRs before alloHCT (p=0.001) were the primary risk factors. This analysis shows that preventive strategies for osteonecrosis in this population should focus on measures to minimize risk factors before alloHCT.