Cytochemical and Ultrastructural Changes in the Osteoclast-like Giant Cells of Giant Cell Tumor of Bone Following Bisphosphonate Administration

Effect of bisphosphonates on bone giant cell tumor recurrence: a meta-analysis

Background

We examined the impact of bisphosphonates as adjuvant therapy on the recurrence of giant cell bone tumors and the impact of various tumor stages and surgical techniques on this effect. Following a thorough examination of the literature up to January 2022, 10 studies including 601 adults with giant cell tumors of the bone were reported; 295 of these subjects received bisphosphonates as adjuvant therapy following surgery, and 306 served as the control group. To examine the possibility of lowering the recurrence of giant cell bone tumors, a comparison between bisphosphonates and a control group was made. In order to evaluate the impact of bisphosphonates as adjuvant therapy on the recurrence of the giant cell bone tumor, odds ratios (OR) with 95% confidence intervals (CIs) were determined. Additionally, the dichotomous technique with a random or fixed-effect model was used to examine the effects of various tumor stages and pertinent surgical procedures.

Results

Patients with giant cell tumors of the bone who received bisphosphonates as adjuvant therapy had significantly lower postoperative recurrence rates outcomes in all subjects with giant cell tumor of bone (OR 0.19; 95% CI 0.12–0.31, p = 0.001), patients with stage I–II giant cell tumors of the bone (OR 0.29; 95% CI 0.11–0.76, p = 0.01), patients with stage III giant cell tumors of the bone (OR 0.17; 95% CI 0.07–0.42, p < 0.001); and post-intralesional curettage (OR 0.18; 95% CI 0.06–0.49, p < 0.001) compared to control. Bisphosphonates were used in participants with giant cell tumors of the bone after broad excision, but there was no discernible difference between the two groups in terms of postoperative recurrence outcomes (OR 0.66; 95% CI 0.11–3.91, p = 0.65).

Conclusions

In patients with giant cell tumors of the bone after intralesional curettage, the use of bisphosphonates as adjuvant therapy may lower the incidence of postoperative recurrence outcomes, but no appreciable difference was identified after extensive resection. According to the observed relationship, using bisphosphonates is advised to lower the likelihood of postoperative recurrence that can happen in patients with giant cell tumors of the bone.

Giant Cell Tumor of Bone: An Update

PURPOSE OF REVIEW

To highlight the new developments in the management of advanced giant cell tumor of bone, a rare locally aggressive benign tumor, which was traditionally managed with surgery alone by either curettage and local adjuvant therapy, wide resection, or marginal excision. Here, we review the current role of systemic therapy for management of locally advanced or metastatic giant cell tumor of bone (GCTB).

RECENT FINDINGS

The elucidation of the pathophysiology of giant cell tumor of bone, especially with regards to the role of nuclear factor kappa B ligand (RANKL), has led to the Food and Drug Administration (FDA) approval of denosumab in the management of locally advanced or metastatic GCTB. For advanced giant cell tumor where surgical resection alone can cause severe morbidity, the paradigm has shifted from local treatment alone to multidisciplinary management with the consideration of use of denosumab.

Role of intravenous zoledronic acid in management of giant cell tumor of bone- A prospective, randomized, clinical, radiological and electron microscopic analysis

BACKGROUND

The primary treatment of Giant cell tumor of bone is surgical management. Bisphosphonates are antiresorptive drugs which inhibit osteoclast mediated bone resorption and shown to have inhibitory effect on various tumors. The present study aims to establish clinical, ultrastructural and radiological response of intravenous zoledronic acid on giant cell tumor of bone.

METHODOLOGY

Design - Prospective randomized controlled study. A group of 30 patients of GCT bone were randomized into two equal groups. Patients in control group did not receive any adjuvant therapy before surgery. Patients in bisphosphonate group received three doses of intravenous zoledronic acid at four weeks interval prior to definitive surgery. The evaluation was done based on size of swelling, VAS score, plain radiograph, MRI and histopathological and Transmission electron microscopic examination findings.

RESULTS

Significant reduction in VAS score (from mean 5.33 to 1.8), increased mineralization particularly at periphery of lesion in plain radiograph, statistically significant increase in mean apoptotic index, P value < 0.0001 (mean 41.46 in bisphosphonate group and 6.06 in control group) was noted in bisphosphonate group. No significant change in tumor volume is noted in MRI. No significant side effects were noted.

DISCUSSION

One distinctive feature of pathogenesis of GCT bone is osteoclastogenesis which causes extensive bone destruction. Use of intravenous Zoledronic acid counteracts this bone destruction. Further, possible antiangiogenic effect of intravenous bisphosphonates inhibits tumor growth and provides symptomatic improvement.

CONCLUSION

IV Zoledronic acid alleviates pain, produce sclerosis and induce apoptosis hence decrease the rate of tumor progression and decrease the rate of local bone destruction, hence they are useful adjuvant to surgery in GCT.

Effect of Intravenous Zoledronic Acid on Histopathology and Recurrence after Extended Curettage in Giant Cell Tumors of Bone: A Comparative Prospective Study

BACKGROUND

Giant cell tumor (GCT) of the bone is known for its locally aggressive behavior and tendency to recur. It is an admixture of rounded or spindle-shaped mononuclear neoplastic stromal cells and multinucleated osteoclast-like giant cells with their proportionate dispersion among the former. Zoledronic acid (a bisphosphonate) is being used in various cancers such as myelomas and metastasis, for osteoporosis with an aim to reduce the resorption of bone, and as an adjuvant treatment for the management of GCT of bone for reduction of local recurrence. We have carried out a prospective comparative study to assess the effect of intravenous infusion of zoledronic acid on histopathology and recurrence of GCT of bone.

MATERIALS AND METHODS

The study was carried out in the biopsy proven GCTs in 37 patients; 15 males and 22 females, in the age range from 17 to 55 years. They were treated with extended curettage. Of these 37 patients, 18 were given three doses of 4 mg zoledronic acid infusion at 3-week intervals and extended curettage was performed 2 weeks after the last infusion whereas the other 19 were treated with extended curettage without zoledronic infusion. The post infusion histopathology of the curetted material was compared with the histopathology of initial biopsy. All the patients were evaluated at 3-month intervals for the first 2 years and then six monthly thereafter, for local recurrence and functional outcome of limb using the Musculoskeletal Tumor Society (MSTS) score.

RESULTS

In postzoledronic infusion cases, the histopathology of samples showed abnormal stromal cells secreting matrix leading to fibrosis and calcification. The type of fibrosis and calcification was different from pathological calcification and fibrosis what is usually observed. There was a good marginalization and solidification of tumors which made surgical curettage easier in six cases in the study group. There was noticeable reduction in the number of giant cells and alteration in morphology of stromal cells to the fibroblastic-fibrocytic series type in comparison to preinfusion histopathology. Recurrence occurred in one case out of 18 patients in infusion group whereas in four cases among 19 patients in control group. The functional results were assessed, and the overall average MSTS score was 27.50 (range 24-30) and 27.00 (range 23.50-30) in the study and control groups, respectively.

CONCLUSIONS

We observed that bisphosphonates reduce osteoclast activity and affects stromal cells in GCT, resulting in the reduction of their numbers and noticeable apoptosis. This results in better marginalization of the lesions and reduced recurrence. Extended curettage of friable GCT became easier and adequate which otherwise might not have been possible.

In Vitro Study of the Effects of Denosumab on Giant Cell Tumor of Bone: Comparison with Zoledronic Acid

Giant cell tumor of bone (GCTB) is a locally aggressive primary bone tumor that contains numerous osteoclasts formed from marrow-derived precursors through receptor activator of nuclear factor κ-B ligand (RANKL), an osteoclast differentiation factor expressed in neoplastic cells of GCTB. Denosumab, a fully human monoclonal antibody targeting RANKL, has recently been used for the treatment of GCTB, and superior treatment effects have been reported. The aim of this work was to elucidate the mechanism of action of denosumab, and the differences between denosumab and zoledronic acid at the level of GCTB cells. We isolated GCTB cells from 3 patients and separated them into osteoclasts, osteoclast precursors and proliferating spindle-shaped stromal cells (the true neoplastic component), and examined the action of denosumab on differentiation, survival and bone resorption activity of osteoclasts. Denosumab and zoledronic acid inhibited osteoclast differentiation from mononuclear cells containing osteoclast precursors. Zoledronic acid inhibited osteoclast survival, whereas an inhibitory effect of denosumab on osteoclast survival was not observed. The inhibitory effect on bone resorption by both agents was confirmed in culture on dentin slices. Furthermore, zoledronic acid showed dose-dependent inhibition of cell growth of neoplastic cells whereas denosumab had no inhibitory effect on these cells. Denosumab has an inhibitory effect on osteoclast differentiation, but no inhibitory effects on survival of osteoclasts or growth of neoplastic cells in GCTBs.

Benign Tumors of the Spine: Has New Chemotherapy and Interventional Radiology Changed the Treatment Paradigm?

STUDY DESIGN

Clinically based systematic review.

OBJECTIVE

To determine the role of (A) medical treatment and (B) interventional radiology as either adjuvant or stand-alone treatment in primary benign bone tumors of the spine.

METHODS

A multidisciplinary panel of spine surgeons, radiation oncologists, and medical oncologists elaborated specific focused questions regarding aneurysmal bone cyst, giant cell tumor, and osteoid osteoma. Denosumab, bisphosphonate, interferon, bone marrow aspirate, doxycycline, thermal ablation, and selective arterial embolization were identified as areas of interest for the article. A systematic review was performed through MEDLINE and EMBASE. Recommendations based on the literature review and clinical expertise were issued using the GRADE system.

RESULTS

The overall quality of the literature is very low with few multicenter prospective studies. For giant cell tumor, combination with Denosumab identified 14 pertinent articles with four multicenter prospective studies. Nine studies were found on bisphosphonates and six for selective arterial embolization. The search on aneurysmal bone cyst and selective arterial embolization revealed 12 articles. Combination with Denosumab, Doxycycline, and bone marrow aspirate identified four, two, and three relevant articles respectively. Eleven focused articles were selected on the role of thermal ablation in osteoid osteoma.

CONCLUSION

Alternative and adjuvant therapy for primary benign bone tumors have emerged. Their ability to complement or replace surgery is now being scrutinized and they may impact significantly the algorithm of treatment of these tumors. Most of the data are still emerging and further research is desirable. Close collaboration between the different specialists managing these pathologies is crucial.

LEVEL OF EVIDENCE

N/A.

Denosumab for the treatment of giant cell tumor of the bone

Giant cell tumor of bone is typically composed of neoplastic stromal cells and non-neoplastic osteoclastic giant cells. RANK-expressing osteoclastic giant cells are recruited by RANK ligand excreted by the stromal cells, and used by these neoplastic cells to create expansion space. Denosumab specifically binds to and inhibits RANK ligand, thereby eradicating osteoclastic giant cells from the tumor and thus reducing osteolytic activity. Clinical studies reported disease stabilization and clinical benefit in terms of reduced pain and analgesics use, avoided surgeries or surgeries with less morbid procedures. Adverse events observed in patients with giant cell tumor of bone were consistent with the known safety profile of denosumab with a very low incidence of hypocalcemia and osteonecrosis. Overall, denosumab was shown to suppress osteolytic activity and slow disease progression and is thus a treatment option for patients with giant cell tumor of bone.

Immunohistochemical comparison of p53, Ki-67, CD68, vimentin, α-smooth muscle actin and alpha-1-antichymotry-psin in oral peripheral and central giant cell granuloma

INTRODUCTION

Giant cell lesions are characterised histologically by multinucleated giant cells in a background of ovoid to spindle-shaped mesenchymal cells. There is a major debate whether these lesions are separate entities or variants of the same disease. Our aim was to study the nature of multinucleated and mononuclear cells from peripheral giant cell granuloma (PGCG), and central giant cell granuloma (CGCG) and giant cell tumor (GCT) of long bones using immunohistochemistry evaluation and to determine whether there is a correlation between recurrence and the markers used.

MATERIALS AND METHODS

Ki-67, p53, Vimentin, smooth muscle specific actin, CD68 and alpha-1-antichymotrypsin were used to study 60 giant cell lesions. These included 26 CGCG, 28 PGCG, and 6 GCT cases using an avidin-biotin-complex immunohistochemistry standard method.

RESULTS

All studied cases showed the same results except the percentage of Ki-67 positive mononuclear cells in PGCG was significantly higher than that of both CGCG and GCT (p<0.05). Interestingly, no statistical correlation between recurrence and the markers used was found.

CONCLUSION

Our results may suggest that these lesions have the same histogenesis. The mononuclear stromal cells, both histiocytic and myofibroblastic, are thought to be responsible for the behavior of these lesions whereas the multinucleated cells are considered as reactive. This might support the argument that PGCG, CGCG and GCT are different variants for the same disease. Further studies using molecular techniques are required to elucidate why some of these lesions behave aggressively than others.

Sustained long-term complete regression of a giant cell tumor of the spine after treatment with denosumab

BACKGROUND CONTEXT

Although giant cell tumors (GCTs) are histologically benign, they may become locally aggressive bone tumors. As these lesions tend to respond poorly to radio- and chemotherapy, currently the standard surgical paradigm for the treatment of spinal GCTs involves en bloc surgical resection. Denosumab is a newly developed monoclonal antibody designed to inhibit the receptor activator of nuclear factor kappa-B ligand (RANKL) which has already been demonstrated to induce marked radiographic responses on GCTs of the appendicular skeleton. Nevertheless, the role of denosumab in the treatment algorithm of GCTs of the spine has not yet been defined.

PURPOSE

To describe the first case of sustained long-term complete clinical and radiographic regression of a GCT of the spine after treatment with the new RANKL antibody denosumab.

STUDY DESIGN

Case report and literature review.

METHODS

The authors describe the case of 22-year-old female patient, harboring a GCT involving the C2 vertebral body and odontoid process, who was treated in monotherapy with denosumab, resulting in complete long-term clinical and radiographic tumor remission.

RESULTS

There were no major side effects associated with the long-term pharmacological treatment with denosumab. From the clinical standpoint, the patient demonstrated complete remission of the disease while under treatment. The 16-month radiographic follow-up demonstrated complete disappearance of the osteolytic process and intense new cortical bone formation with restoration of the bone integrity of the C2 vertebral body.

CONCLUSIONS

This is the first report of sustained long-term complete clinical and radiographic regression of a GCT of the spine after treatment with the new RANKL antibody denosumab. Although future long-term follow-up studies are still necessary to establish important key points regarding the best therapeutic protocol with such a new drug (such as the optimal time frame to keep the patient under treatment), denosumab promises to bring major changes to the current therapeutic paradigm for GCTs of the spine, which, up to now, has strongly relied on en bloc surgical resection.

Segmental composite porous scaffolds with either osteogenesis or anti-bone resorption properties tested in a rabbit ulna defect model

A functional biomaterial with a therapeutic effect is desirable as an adjuvant therapy to enhance bone formation and prevent local recurrence of bone tumours, especially when the resection margins are not identifiable. In this study, novel composite materials were developed with dual properties of osteopromotion and bone resorption to mimic the tumour inhibition effect, including water-soluble phosphorylated chitosan (P-chitosan) for increasing osteoblasts activity and disodium (1 → 4)-2-deoxy-2-sulphoamino-β-d-glucopyranuronan (S-chitosan) for inhibiting bone resorption activity. First, P-chitosan and S-chitosan were respectively incorporated into two kinds of PLGA/TCP-based scaffold, i.e. PLGA-TCP-P-chitosan (P/T/P-chitosan) and PLGA-TCP-S-chitosan (P/T/S-chitosan) scaffolds. We subsequently tested combined scaffolds of PLGA-TCP-P-S-P-chitosan (P/T/PSP-chitosan) made of P/T/P-chitosan and P/T/S-chitosan to assess their integral effect, on enhancement of bone formation with P/T/P-chitosan and inhibition of tissue regeneration with P/T/S-chitosan, in an established rabbit ulnar bone defect model to imitate bone resection post-bone tumour. To compare bone healing in the defects, the P/T/P-chitosan group was regarded as a bone formation enhancement group, while the P/T group served as a control. Bone mineral density (BMD) in the P/T/P-chitosan and P/T/PSP-chitosan groups were found to be significantly higher than those in the P/T group, while that in the P/T/P-chitosan group was greater than that in the P/T/PSP-chitosan group (p < 0.05). These findings demonstrated that P/T/PSP-chitosan scaffolds possessed more osteogenic potential than the P/T scaffold but less osteogenic effect than the P/T/P-chitosan scaffold, as the S-chitosan component inhibited the activities of osteoblasts for bone formation. These findings implied a dual function of the designed P/T/PSP-chitosan for further preclinical validation and potential applications in the prevention of local recurrence and for enhancing bone repair after bone tumour resection. Copyright © 2013 John Wiley & Sons, Ltd.

Comparison of the anti-tumor effects of denosumab and zoledronic acid on the neoplastic stromal cells of giant cell tumor of bone

Denosumab and Zoledronic acid (ZOL) are two antiresorptive drugs currently in use for treating osteoporosis. They have different mechanisms of action but both have been shown to delay the onset of skeletal-related events in patients with giant cell tumor of bone (GCT). However, the anti-tumor mechanisms of denosumab on the neoplastic GCT stromal cells remain unknown. In this study, we focused on the direct effects of denosumab on the neoplastic GCT stromal cells and compared with ZOL. The microscopic view demonstrated a reduced cell growth in ZOL-treated but not in denosumab-treated GCT stromal cells. ZOL was found to exhibit a dose-dependent inhibition in cell growth in all GCT stromal cell lines tested and cause apoptosis in two out of three cell lines. In contrast, denosumab only exerted a minimal inhibitory effect in one cell line and did not induce any apoptosis. ZOL significantly inhibited the mRNA expression of receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) in two GCT stromal cell lines whereas their protein levels remained unchanged. On the contrary, denosumab did not regulate RANKL and OPG expression at both mRNA and protein levels. Moreover, the protein expression of Macrophage Colony-Stimulating Factor (M-CSF), Alkaline Phosphatase (ALP), and Collagen α1 Type I were not regulated by denosumab and ZOL either. Our findings provide new insights in the anti-tumor effect of denosumab on GCT stromal cells and raise a concern that tumor recurrence may occur after the withdrawal of the drug.

Reversibility of pamidronate-associated glomerulosclerosis

Bisphosphonates such as pamidronate are widely used in the treatment of patients with lytic bony lesions secondary to breast cancer or multiple myeloma, yet they have been associated with deterioration of renal function and histopathological changes in the kidney. There have been recent reports associating the use of pamidronate with the development of the collapsing variant of focal segmental glomerulosclerosis (CFSGS), a rapidly progressive variant of focal segmental glomerulosclerosis that leads to end-stage renal disease. We describe five patients who developed worsening renal function, proteinuria, and nephrotic syndrome while taking pamidronate; three of them had biopsy-proven CFSGS. Pamidronate was discontinued, and a longitudinal follow-up was performed for 10 to 23 months. One patient was able to discontinue hemodialysis, and all patients experienced improvement in renal function and a decrease in proteinuria. In some patients who develop pamidronate-associated CFSGS, renal damage appears to be reversible if the syndrome is recognized early and pamidronate is stopped.

Analysis of the cytotoxicity of differentially sized titanium dioxide nanoparticles in murine MC3T3-E1 preosteoblasts

There is an increased use of nanophase titanium dioxide (TiO(2)) in bone implants and scaffolds. However, nano-debris is generated at the bone-biomaterial interface. Therefore, TiO(2) nanoparticles (NPs) of many sizes were investigated for cytotoxic effects on murine MC3T3-E1 preosteoblasts. These TiO(2) NPs induced a time- and dose-dependent decrease in cell viability. There was a significant increase in lactate dehydrogenase (LDH) release, apoptosis and mitochondrial membrane permeability following short-term exposure of the cells to TiO(2) NPs. These NPs also increased granulocyte-macrophage colony stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) gene expression. Compared with the 32 nm TiO(2) NPs, 5 nm TiO(2) NPs were more toxic, induced more apoptosis, increased mitochondrial membrane permeability and stimulated more GM-CSF expression at a high concentration (≥100 μg/ml). The results implied that the differential toxicity was associated with variations in size, so more attention should be given to the toxicity of small NPs for the design of future materials for implantation.

Pamidronate, farnesyl transferase, and geranylgeranyl transferase-I inhibitors affects cell proliferation, apoptosis, and OPG/RANKL mRNA expression in stromal cells of giant cell tumor of bone

Giant cell tumor (GCT) is the most common nonmalignant primary bone tumor reported in Hong Kong. It usually affects young adults between the ages of 20 and 40. This tumor is well known for its potential to recur following treatment. To date no effective adjuvant therapy exists for GCT. Our project aimed to study the effects of pamidronate (PAM), farnesyl transferase inhibitor (FTI-277), geranylgeranyl transferase inhibitor (GGTI-298), and their combinations on GCT stromal cells (SC). Individual treatment with PAM, FTI-277, and GGTI-298, inhibited the cell viability and proliferation of GCT SC in a dose-dependent way. Combination of FTI-277 with GGTI-298 caused synergistic effects in reducing cell viability, and its combination index was 0.49, indicating a strong synergism. Moreover, the combination of FTI-277 with GGTI-298 synergistically enhanced cell apoptosis and activated caspase-3/7, -8, and -9 activities. PAM induced cell-cycle arrest at the S-phase. The combination of PAM with GGTI-298 significantly increased OPG/RANKL mRNA ratio and activated caspase-3/7 activity. Our findings support that the combination of bisphosphonates with GGTIs or FTIs with GGTIs may be used as potential adjuvants in the treatment of GCT of bone.

Giant cell tumor of the distal femur associated with complete tumor necrosis

Giant cell tumor is a benign tumor of bone with a predilection for juxta-articular locations. Although not malignant, giant cell tumor often exhibits unpredictable and locally aggressive behavior, and in rare cases can metastasize in the absence of histologic malignancy. Partial tumor necrosis has been infrequently reported within typical giant cell tumor. A 17-year-old girl presented with a right distal femur giant cell tumor associated with complete tumor necrosis on histopathologic analysis. The etiology, prevalence, and implications of complete necrosis in previously untreated giant cell tumor of bone remain unclear, as there are no previously published reports. Despite the complete necrosis evident in our patient, she nonetheless presented with pain. There were no radiographic signs of the necrotic tumor space remodeling with new bone. The patient was treated with standard extended intralesional curetting through a generous cortical window permitting visualization of the entire lesion, and systematic high speed burring and thermal electrocautery ablation of the periphery, followed by micro particulate allogenic bone grafting. At short-term follow-up, she had healed well with no evidence of tumor recurrence. This article presents the first case, to our knowledge, of complete spontaneous tumor necrosis in a previously untreated bone giant cell tumor. Increased understanding of spontaneous tumor necrosis associated with giant cell tumor may help guided future targeted medical and surgical treatment modalities.

Bisphosphonate treatment of aggressive primary, recurrent and metastatic Giant Cell Tumour of Bone

Background

Giant cell tumour of bone (GCTB) is an expansile osteolytic tumour which contains numerous osteoclast-like giant cells. GCTB frequently recurs and can produce metastatic lesions in the lungs. Bisphosphonates are anti-resorptive drugs which act mainly on osteoclasts.

Method

In this study, we have examined clinical and radiological outcomes of treatment with aminobisphosphonates on 25 cases of aggressive primary, recurrent and metastatic GCTB derived from four European centres. We also analysed in vitro the inhibitory effect of zoledronic acid on osteoclasts isolated from GCTBs.

Results

Treatment protocols differed with several different aminobisphosphonates being employed, but stabilisation of disease was achieved in most of these cases which were refractory to conventional treatment. Most inoperable sacral/pelvic tumours did not increase in size and no further recurrence was seen in GCTBs that had repeatedly recurred in bone and soft tissues. Lung metastases did not increase in size or number following treatment. Zoledronic acid markedly inhibited lacunar resorption by GCTB-derived osteoclasts in vitro.

Conclusion

Our findings suggest that bisphosphonates may be useful in controlling disease progression in GCTB and that these agents directly inhibit GCTB - derived osteoclast resorption. These studies highlight the need for the establishment of standardised protocols to assess the efficacy of bisphosphonate treatment of GCTB.

p53 reaction to apoptosis induced by hydroxyapatite nanoparticles in rat macrophages

The effects and mechanism of hydroxyapatite (HAP) nanoparticles (NPs) on the induction of cytotoxicity and apoptosis in rat macrophages was evaluated by testing the antiproliferative effect of HAP NPs with agar overlay and direct contact methods. The apoptotic phenotype of the macrophages was observed by transmission electron microscopy (TEM), and the variation of transcription and expression of a cell apoptosis related gene (p53) was determined by semiquantitative RT-PCR and western blotting. The results showed that a dose-dependent proliferative inhibition of macrophages was induced by HAP NPs (30-80 nm) at concentrations between 20 and 200 microg/mL. The characteristic morphological changes of apoptosis were observed in macrophages after treatment with HAP NPs for 24 h. Furthermore, p53 mRNA levels significantly increased when macrophages were incubated with 200 microg/mL HAP NPs (p < 0.01). Western blot analysis showed that 100 microg/mL HAP NPs upregulated p53. The conclusion is that HAP NPs can induce p53 expression through phosphorylation, which promotes downstream genes and finally results in cell apoptosis. Moreover, p53 may be one of the ideal indictors to evaluate the biological safety of ceramic nanoparticles.

Bisphosphonates reduce local recurrence in extremity giant cell tumor of bone: a case-control study

BACKGROUND

Giant cell tumor (GCT) of bone is a benign but locally aggressive tumor that is characterized by the presence of mononuclear stromal cells and multinucleated giant cells. Although topical adjuvants have been used in the past, local recurrence following intralesional excision of GCT of bone continues to remain a problem. The use of bisphosphonates as an anti-osteoclastic agent in the management of osteolytic bone metastases is well accepted. Furthermore in vitro studies have shown that bisphosphonates also induce apoptosis in GCT stromal cells. Therefore our clinical study aims to investigate whether the administration of bisphosphonate as an adjuvant can further decrease local recurrence following the surgical treatment of GCT of bone.

METHOD

A retrospective case-control study was performed between 1988 and 2004. Forty-four patients with histological diagnosed appendicular GCT were included. Intralesional curettage or wide excision of the lesions was followed with cementation or biological reconstruction. Additional intravenous and oral bisphosphonates were given peri-operatively to 24 patients who were treated between 1998 and 2004. The average follow-up of the control group was 115 months while that of the treatment group was 48 months.

RESULTS

In the bisphosphonate treated group, 1 of 24 patients (4.2%) developed local recurrence. In the control group, 6 of 20 patients (30%) developed local recurrence. The difference in the recurrence rate was statistically significant between the bisphosphonate treatment group and the control group (Log Rank test p=0.056). The effect of reduction of local recurrence was significant in patients with stage III diseases. Patients treated with bisphosphonate did not report any untoward effects.

CONCLUSION

Clinical use of bisphosphonates as an adjuvant therapy for giant cell tumor of bone demonstrated a lower local recurrence rate. The clinical response seems to be more promising in stage III diseases.

Giant cell tumour of bone: morphological, biological and histogenetical aspects

The giant cell tumour of bone (GCT) is a locally aggressive intraosseous neoplasm of obscure biological behaviour. Although well defined in clinical, radiological and histological terms, detailed information on its biological development is still relatively incomplete. The tumoral tissue consists of three cell types--the neoplastic giant cell tumour stromal cells (GCTSC), representing the proliferative fraction, secondarily recruited mononuclear histiocytic cells (MNHC) and multinuclear giant cells (MNGC). These cellular components interact together with factors that have a role in regulating osteoclast function in normal bone tissue (e.g. RANK, RANKL, OPG, M-CSF). Recent publications suggest that the neoplastic stromal cells express differentiation features of mesenchymal stem cells. Further research of the pathogenesis of GCT as well as the complex interactions of its cellular populations may provide the knowledge necessary for developing approaches for a biological-based therapy of this neoplasm.

Giant cell tumor of bone

Giant cell tumor is a common benign bone tumor that possesses specific features including location at the end of long bone, a strong tendency toward local recurrence, and the rare capacity to metastasize to the lungs. Preferred treatment usually consists of extensive curettage and filling of the cavity with bone graft or cement. Debate still exists about the usefulness of local adjuvant treatment. Functional outcome is usually very good.

Treatment of a central giant cell granuloma with intralesional corticosteroid

A recurrent central giant cell granuloma in a 14-year-old girl in the anterior region of the mandible was treated successfully by intralesional injection of corticosteroid.

Bisphosphonates induce apoptosis of stromal tumor cells in giant cell tumor of bone

Giant cell tumour of bone (GCT) is an aggressive primary neoplasm that results in the production of osteolytic lesions. Stromal cells, which form the main neoplastic component of this tumor, regulate the formation of osleoclast-like giant cells that are ultimately responsible for bone destruction. Bisphosphonates prevent bone resorption by inhibiting osteoclast activity and promoting osteoclast apoptosis, and they have been known to induce apoptosis of primary neoplastic cells such as those in breast and prostate cancers. We hypothesized that in bisphosphonates may induce apoptosis not only in osteoclast-like giant cells but also in neoplastic stromal cells of GCT both in vitro and in vivo. Twelve patients with GCT were treated with weekly injections of pamidronate for a period of 6 weeks prior to surgery. GCT specimens were collected at the time of biopsy and during definitive surgery. TUNEL assay was used to evaluate apoptotic DNA fragmentation in cells. In addition, twelve GCT primary cultures from these patients were treated with zoledronate, pamidronate, or alendronate for 48 hours at different doses (3, 30, or 150 microM) and subjected to apoptosis assay by flow cytometry following fluorescent Annexin-V labeling. The results showed that pamidronate significantly induced apoptosis in both osteoclast-like giant cells and stromal tumor cells, in vivo. All three bisphosphonates caused substantial apoptosis of stromal tumor cells in cultures. Zoledronate was the most potent reagent, resulting in an average cell death of 27.41% at 150 microM, followed by pamidronate (22.23%) and alendronate (15.3%). Our observations suggest that these drugs may be considered as potential adjuvants in the treatment of GCT.