Effects of bone morphogenetic protein-2 on proliferation and angiogenesis in oral squamous cell carcinoma

Clinical Application of 3D-Printed Patient-Specific Polycaprolactone/Beta Tricalcium Phosphate Scaffold for Complex Zygomatico-Maxillary Defects

(1) Background: In the present study, we evaluated the efficacy of a 3D-printed, patient-specific polycaprolactone/beta tricalcium phosphate (PCL/β-TCP) scaffold in the treatment of complex zygomatico-maxillary defects. (2) Methods: We evaluated eight patients who underwent immediate or delayed maxillary reconstruction with patient-specific PCL implants between December 2019 and June 2021. The efficacy of these techniques was assessed using the volume and density analysis of computed tomography data obtained before surgery and six months after surgery. (3) Results: Patients underwent maxillary reconstruction with the 3D-printed PCL/β-TCP scaffold based on various reconstructive techniques, including bone graft, fasciocutaneous free flaps, and fat graft. In the volume analysis, satisfactory volume conformity was achieved between the preoperative simulation and actual implant volume with a mean volume conformity of 79.71%, ranging from 70.89% to 86.31%. The ratio of de novo bone formation to total implant volume (bone volume fraction) was satisfactory with a mean bone fraction volume of 23.34%, ranging from 7.81% to 66.21%. Mean tissue density in the region of interest was 188.84 HU, ranging from 151.48 HU to 291.74 HU. (4) Conclusions: The combined use of the PCL/β-TCP scaffold with virtual surgical simulation and 3D printing techniques may replace traditional non-absorbable implants in the future owing to its accuracy and biocompatible properties.

Signaling pathways promoting epithelial mesenchymal transition in oral submucous fibrosis and oral squamous cell carcinoma

Epithelial-mesenchymal transition (EMT) is a critical process that occurs during the embryonic development, wound healing, organ fibrosis and the onset of malignancy. Emerging evidence suggests that the EMT is involved in the invasion and metastasis of cancers. The inflammatory reaction antecedent to fibrosis in the onset of oral submucous fibrosis (OSF) and the role of EMT in its malignant transformation indicates a hitherto unexplored involvement of EMT. This review focuses on the role of EMT markers which are regulators of the EMT mediated complex network of molecular mechanisms involved in the pathogenesis of OSF and OSCC. Further the gene enrichment analysis and pathway analysis supports the association of the upregulated and downregulated genes in various EMT regulating pathways.

Efficacy of three-dimensionally printed polycaprolactone/beta tricalcium phosphate scaffold on mandibular reconstruction

It has been demonstrated that development of three-dimensional printing technology has supported the researchers and surgeons to apply the bone tissue engineering to the oromandibular reconstruction. In this study, poly caprolactone/beta tricalcium phosphate (PCL/β-TCP) scaffolds were fabricated by multi-head deposition system. The feasibility of the three-dimensionally (3D) -printed PCL/β-TCP scaffolds for mandibular reconstruction was examined on critical-sized defect of canine mandible. The scaffold contained the heterogeneous pore sizes for more effective bone ingrowth and additional wing structures for more stable fixation. They were implanted into the mandibular critical-sized defect of which periosteum was bicortically resected. With eight 1-year-old male beagle dogs, experimental groups were divided into 4 groups (n = 4 defects per group, respectively). (a) no further treatment (control), (b) PCL/β-TCP scaffold alone (PCL/TCP), (c) PCL/β-TCP scaffold with recombinant human bone morphogenetic protein-2 (rhBMP-2) (PCL/TCP/BMP2) and (d) PCL/β-TCP scaffold with autogenous bone particles (PCL/TCP/ABP). In micro-computed tomography, PCL/TCP/BMP2 and PCL/TCP/ ABP groups showed significant higher bone volume in comparison to Control and PCL/TCP groups (P < 0.05). In histomorphometric analysis, a trend towards more bone formation was observed in PCL/TCP/BMP2 and PCL/TCP/ABP groups, but the results lacked statistical significance (P = 0.052). Within the limitations of the present study, 3D-printed PCL/β-TCP scaffolds showed acceptable potential for oromandibular reconstruction.

A meta-analysis of bone morphogenetic protein-2 versus iliac crest bone graft for the posterolateral fusion of the lumbar spine

The impact of autologous iliac crest bone graft versus BMP-2 to improve fusion rates for posterolateral fusion (PLF) of the lumbar spine remains unanswered. Single-institution-centered data dominate the literature, providing results that may be contradictory or inconclusive. The aim of this paper is to analyze data pooled from multiple well-controlled studies that examined both ICBG and BMP-2 for use in PLF. This meta-analysis also provides details of success in different subsets of patients with variable risk factors for delayed and non-unions. Six high-quality randomized clinical trials were selected. Efficacy, morbidity, quality of life, and safety were compared between the BMP-2 group and the ICBG group. A total of 908 patients were included in the study. At 24 months, 94% of patients achieved fusion in the BMP-2 group and 83% in the ICBG group. At 6 and 12 months, the fusion was also greater in the BMP-2 group (86% vs. 60% and 88% vs. 80%, respectively). Surgical time, intraoperative blood loss, and hospitalization days also showed significant differences in favor of the experimental group (p < 0.01). There were no differences between two groups in the Oswestry Disability Index, 36-Item Short Form Health Survey and Back Pain Score, whereas a greater number of additional surgical procedures were performed in the ICBG group (p = 0.001). In conclusion, the use of BMP-2 in PLF reduced the surgical morbidity and had more beneficial effects on the fusion rate. The quality of life based on clinical scores was the same in both groups.

Evaluation of BMP-2 Enhances the Osteoblast Differentiation of Human Amnion Mesenchymal Stem Cells Seeded on Nano-Hydroxyapatite/Collagen/Poly(l-Lactide)

Background: The aim of this study is to evaluate the effects of recombinant human bone morphogenetic protein 2 (rhBMP-2), human amnion mesenchymal stem cells (hAMSCs), and nanohydroxyapatite/collagen/poly(l-lactide) (nHAC/PLA) in tissue engineering to provide potential approaches for periodontal bone regeneration. Methods: hAMSCs were isolated from discarded amniotic membrane samples and cultured in vitro. Alkaline phosphatase (ALP) staining and alizarin red staining were performed to evaluate the osteoblast (OB) differentiation ability of hAMSCs. Three groups were divided: the experimental group (cells transfected with pcDNA3.1-rhBMP-2), the blank group (cells without gene transfection), and the control group (cells transfected with empty plasmid). RT-PCR and western blot were used to examine whether rhBMP-2 has been successfully expressed. 3-(4,5)-dimethylthiahiazol(-z-y1)-3,5-di-phenytetrazo-liumromide assay (MTT) was done to detect the effect of rhBMP-2 on hAMSCs seeded on nHAC/PLA. ALP activity, mineral formation assay, calcium, phosphate and osteocalcin (OCN) content, and OCN and RUNX2 expression of hAMSCs were detected to evaluate osteogenic differentiation capability of rhBMP-2 on hAMSCs seeded on nHAC/PLA. Results: hAMSCs exhibited intense ALP staining, obvious calcium deposition, and mineralization nodules, and rhBMP-2 were highly expressed in the experimental group. The proliferation of the hAMSCs with rhBMP-2 on nHAC/PLA was significantly higher than the cells without rhBMP-2, and the cells all increased in a time-dependent manner. rhBMP-2 significantly increased the OCN and phosphate content, mineral formation, ALP activity, osteogenic biomarkers OCN, and Runx2, and decreased calcium content in hAMSCs seeded on the nHAC/PLA scaffold. Conclusions: This finding demonstrated that hAMSCs has an ideal OB differentiation ability. rhBMP-2 facilitates the proliferation and osteogenesis of hAMSCs. The nHAC/PLA could act as a good scaffold for hAMSCs seeding, proliferation, and osteogenic differentiation. The application of rhBMP-2, nHAC/PLA, and hAMSCs in tissue engineering may offer promising possibilities for periodontal bone regeneration.

Comparison of the use of rhBMP-7 versus iliac crest autograft in single-level lumbar fusion: a meta-analysis of randomized controlled trials

The aim of this study was to evaluate the safety and clinical effectiveness of rhBMP-7 (or osteogenic protein-1) versus that of autogenous iliac crest bone graft (ICBG) in single-level posterolateral fusion (PLF) of the lumbar spine. A systematic search of all articles published through July 1, 2016 was conducted in databases such as PubMed, EMBASE, Scopus, and the Cochrane Collaboration Library. Randomized controlled trials (RCTs) that compared rhBMP-7 with ICBG for the treatment of single-level degenerative spondylolisthesis, provided the fusion rate, clinical success rate, safety and adverse events report, operation time, and hospital stay durations as the outcome were assessed. As a result, a total of five RCTs involving 539 patients met the inclusion criteria. The outcomes of subgroup analysis demonstrated that when compared with autogenous ICBG, rhBMP-7 appear to yield lower fusion rates in instrumented posterolateral fusion patients (RR = 0.76, 95% CI [0.60, 0.98], P = 0.03), despite the test for overall fusion rates suggested that there was no significant difference between the two groups (RR = 0.89, 95% CI [0.78, 1.02], P = 0.09). Patients treated with OP-1 had shorter operation times versus those treated with ICBG (WMD = -16.70,95% CI [-25.83, -7.57], P = 0.0003). Additionally, the outcomes demonstrated a lack of significant differences between rhBMP-7 and ICBG in terms of clinical success of ODI, overall adverse events, revision rates and duration of hospitalization. In conclusion, with the exception of reducing the operation time, our review suggests that the use of the rhBMP-7 instead of ICBG produce no any additional beneficial effect on the fusion rates, clinical success of ODI, overall adverse events, revision rates and duration of hospitalization in single level PLF. On the contrary, it appeared to yield lower fusion rate in the instrumented posterolateral fusion patients and cannot be recommended as an effective tool for this set of patients.

Effects of rhBMP-2 gene transfection to periodontal ligament cells on osteogenesis

The present study aims to investigate the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the osteogenesis of periodontal ligament (PDL) cells. The expression vector of rhBMP-2 (pcDNA3.1-rhBMP-2) was established. PDL cells were obtained through the enzymatic digestion and tissue explant methods and verified by immunohistochemistry. Cells were classified into experimental (cells transfected with pcDNA3.1/rhBMP-2-EGFP), blank (cells with no transfection) and control group (cells transfected with empty plasmid). rhBMP-2 expression was assessed via Western blotting analysis. The mineralization ability, alkaline phosphatase (ALP) activity and level of related osteogenic biomarkers were detected to evaluate the osteogenic characteristics of PDL cells. The rhBMP-2 expression vector (pcDNA3.1-rhBMP-2) was successfully established. Primary PDL cells displayed a star or long, spindle shape. The cultured cells were long, spindle-shaped, had a plump cell body and homogeneous cytoplasm and the ellipse nucleus contained two or three nucleoli. Cells displayed a radial, sheaf-like or eddy-like arrangement after adherence growth. Immunohistochemical staining confirmed that cells originated from mesenchymal opposed to epithelium. The experimental group exhibited an enhanced mineralization ability, higher ALP activity and increased expression of rhBMP-2 and osteogenic biomarkers (Runx2, collagen type I and osteocalcin) than the blank and control group. The present study demonstrated that rhBMP-2 transfection enhances the osteogenesis of PDL cells and provides a possibility for the application of rhBMP-2 expression products in dental disease treatment.

Recombinant Human Bone Morphogenetic Protein-2 in Development and Progression of Oral Squamous Cell Carcinoma

Bone morphogenetic proteins (BMPs), belonging to the transforming growth factor-β superfamily, regulate many cellular activities including cell migration, differentiation, adhesion, proliferation and apoptosis. Use of recombinant human bone morphogenic protein?2 (rhBMP?2) in oral and maxillofacial surgery has seen a tremendous increase. Due to its role in many cellular pathways, the influence of this protein on carcinogenesis in different organs has been intensively studied over the past decade. BMPs also have been detected to have a role in the development and progression of many tumors, particularly disease-specific bone metastasis. In oral squamous cell carcinoma - the tumor type accounting for more than 90% of head and neck malignancies- aberrations of both BMP expression and associated signaling pathways have a certain relation with the development and progression of the disease by regulating a range of biological functions in the altered cells. In the current review, we discuss the influence of BMPs -especially rhBMP-2- in the development and progression of oral squamous cell carcinoma.

Bone morphogenetic protein-2 and tumor growth: Diverse effects and possibilities for therapy

Concern regarding safety with respect to the clinical use of human bone morphogenetic protein-2 (BMP-2) has become an increasingly controversial topic. The role of BMP-2 in carcinogenesis is of particular concern. Although there have been many studies of this topic, the results have been contradictory and confusing. We conducted a systematic review of articles that are relevant to the relationship or effect of BMP-2 on all types of tumors and a total of 97 articles were included. Studies reported in these articles were classified into three major types: "expression studies", "in vitro studies", and "in vivo studies". An obvious pattern was that those works that hypothesize an inhibitory effect for BMP-2 most often examined only the proliferative properties of the tumor cells. This subset of studies also contained an extraordinary number of contradictory findings which made drawing a reliable general conclusion impossible. In general, we support a pro-tumorigenesis role for BMP-2 based on the data from these in vitro cell studies and in vivo animal studies, however, more clinical studies should be carried out to help make a firm conclusion.

RhBMP-2 Activates Hippo Signaling through RASSF1 in Esophageal Cancer Cells

Despite that recombinant human bone morphogenetic protein-2 (rhBMP-2) has been reported as a stimulatory effecter of cancer cell growth because of its characteristic like morphogen, the biological functions of rhBMP-2 in human esophageal cancer cells are unknown. The purpose of this study was to investigate whether rhBMP-2 has an inhibitory effect on the growth of human esophageal squamous carcinoma cells (ESCC). RhBMP-2 significantly inhibited proliferation of ESCC cells in a dose-dependent manner in the MTT assay. Cell cycle arrest at the G1 phase was induced 24 h after rhBMP2 treatment. RhBMP-2 also reduced cyclin D₁, cyclin-dependent kinase (CDK) 4 and CDK 6 activities, and stimulated p-Smad1/5/8, p53, and p21 levels at 12 h. In contrast, rhBMP-2 diminished poly (ADP-ribose) polymerase (PARP) protein expression levels and activated cleaved PARP, cleaved caspase-7, and cleaved-caspase 9 levels in ESCC cells. In addition, rhBMP-2 increased MST1, MOB1, and p-YAP protein levels and the RASSF1 binds Mst1 more upon treatment with rhBMP2. The induced p-YAP expression in TE-8 and TE-12 cells by rhBMP-2 was reversed by the RASSF1 knockdown. In vivo study, rhBMP-2 decreased tumor volume following subcutaneous implantation and showed higher radiologic score (less bony destruction) after femoral implantation compared to those in a control group. These results suggest that rhBMP-2 inhibits rather than activates proliferation of human esophageal cancer cells which is mediated through activating the hippo signaling pathway.

Association Between BMP-2 and Carcinogenicity

STUDY DESIGN

Literature review.

OBJECTIVE

To evaluate the association between recombinant human bone morphogenetic protein-2 (rhBMP-2) and malignancy.

SUMMARY OF BACKGROUND DATA

The use of rhBMP-2 in spine surgery has been the topic of much debate as studies assessing the association between rhBMP-2 and malignancy have come to conflicting conclusions.

METHODS

A systematic review of the literature was performed using the PubMed-National Library of Medicine/National Institute of Health databases. Only non-clinical studies directly addressing BMP-2 and cancer were included. Articles were categorized by study type (animal, in vitro cell line/human/animal), primary malignancy, cancer attributes, and whether BMP-2 was pro-malignancy or not.

RESULTS

A total of 4,131 articles were reviewed. Of those, 515 articles made reference to both BMP-2 and cancer, 99 of which were found to directly examine the role of BMP-2 in cancer. Seventy-five studies were in vitro and 24 were animal studies. Forty-three studies concluded that BMP-2 enhanced cancer function, whereas 18 studies found that BMP-2 suppressed malignancy. Thirty-six studies did not examine whether BMP-2 enhanced or suppressed cancer function. Fifteen studies demonstrated BMP-2 dose dependence (9 enhancement, 6 suppression) and one study demonstrated no dose dependence. Nine studies demonstrated BMP-2 time dependence (6 enhancement, 3 suppression). However, no study demonstrated that BMP-2 caused cancer de novo.

CONCLUSION

Currently, conflicting data exist with regard to the effect of exogenous BMP-2 on cancer. The majority of studies addressed the role of BMP-2 in prostate (17%), breast (17%), and lung (15%) cancers. Most were in vitro studies (75%) and examined cancer invasiveness and metastatic potential (37%). Of 99 studies, there was no demonstration of BMP-2 causing cancer de novo. However, 43% of studies suggested that BMP-2 enhances tumor function, motivating more definitive research on the topic that also includes clinically meaningful dose- and time-dependence.

LEVEL OF EVIDENCE

2.

Cancer stem cells and stemness markers in oral squamous cell carcinomas

Head and neck squamous cell carcinoma (HNSCC) is one of the world top ten most common cancers with its highest occurrence in the Indian subcontinent and different aggressive and etiological behavioural patterns. The scenario is only getting worst with the 5 year survival rates dropping to 50%, persistent treatment failures and frequent cases of relapse/recurrence. One of the major reasons for these failures is the presence of cancer stem cells (CSCs), a small population of cancer cells that are highly tumourigenic, capable of self-renewal and have the ability to differentiate into cells that constitute the bulk of tumours. Notably, recent evidence suggests that cancer stem cells are especially resistant to conventional therapy and are the "drivers" of local recurrence and metastatic spread. Specific markers for this population have been investigated in HNSCC in the hope of developing a deeper understanding of their role in oral cancer pathogenesis, elucidating novel biomarkers for early diagnosis and newer therapeutic strategies. This review covers the fundamental relevance of almost all the CSC biomarkers established to date with a special emphasis on their impact in the process of oral tumourigenesis and their potential role in improving the diagnosis, prognosis and treatment of OSCC patients.

Effects of recombinant human bone morphogenetic protein 7 (rhBMP-7) on the behaviour of oral squamous cell carcinoma: a preliminary in vitro study

We investigated the effects of recombinant human bone morphogenetic protein-7 (rhBMP-7) on the behaviour of oral keratinocytes and head and neck squamous cell carcinoma (SCC) cells in vitro. Expression of all three BMP receptors was high (p<0.01), and rhBMP-7 exhibited significant dose-related inhibitory effects on the doubling time and viability of cancer cells (p<0.01), but not on the proliferation or viability of oral keratinocytes. It elicited no significant effect on the invasion of Matrigel in SCC of the head and neck. Results indicate that in cell culture, rhBMP-7 exerts antineoplastic effects. This should be tested in an orthotopic animal model to more closely replicate in vivo effects.

A multicenter study on expressions of vascular endothelial growth factor, matrix metallopeptidase-9 and tissue inhibitor of metalloproteinase-2 in oral and maxillofacial squamous cell carcinoma

Background:

Vascular endothelial growth factor (VEGF), matrix metallopeptidase-9 (MMP-9) and tissue inhibitor of metalloproteinase-2 (TIMP-2) are potential markers of oral and maxillofacial squamous cell carcinoma (SCC).

Objectives:

To explore the association between expression of VEGF, MMP-9 and TIMP-2 in oral and maxillofacial SCC and clinicopathological factors.

Patients and Methods:

Immunohistochemical Envision method was used to analyze the expression of VEGF, MMP-9 and TIMP-2 in 54 cases of oral and maxillofacial SCC and the association with clinicopathological factors such as clinical staging and lymphatic metastasis.

Results:

Brownish-yellow staining is correlated with positive expression of VEGF, MMP-9 and TIMP-2. Positive expression of VEGF and MMP-9 was correlated with lymphatic metastasis, and their positive expression rates were significantly higher in patients with lymphatic metastasis than those without it (VEGF: χ² = 30.00; P = 0.001; MMP-9: χ² = 18.27, P = 0.001). The positive expression rate of MMP-9 decreased at earlier clinical stages (P < 0.05). Positive expression of TIMP-2 was correlated with lymphatic metastasis, clinical staging and T classification. The positive rate of TIMP-2 expression in patients with lymphatic metastasis was significantly lower than those without it (χ² = 26.74, P = 0.002), which significantly reduced with increasing clinical stage and T classification (P < 0.05).

Conclusions:

Lymphatic metastasis in patients with oral and maxillofacial SCC is closely related to the positive expression of VEGF, MMP-9 and TIMP-2. MMP-9 and TIMP-2 can affect the progression of cancer, which is valuable for studies on oral and maxillofacial SCC genes.

Does the calcification of adamantinomatous craniopharyngioma resemble the calcium deposition of osteogenesis/odontogenesis?

AIMS

Calcification in adamantinomatous craniopharyngioma (ACP) is troublesome for surgical intervention. The aim of this study was to examine the osteogenic proteins that play important roles in the calcium deposition of the odontogenic/osteogenic tissues in craniopharyngioma.

METHODS AND RESULTS

Craniopharyngiomas (n = 89) were investigated for the presence and expression pattern of the osteoinductive/odontoinductive factor bone morphogenetic protein-2 (Bmp2) and two osteoblastic differentiation makers, Runt-related transcription factor-2 (Runx2) and Osterix, using immunohistochemistry and Western blotting. Our results showed that Bmp2, Runx2 and Osterix levels increased in cases with high calcification and correlated positively with the degree of calcification in ACP, whereas they showed little or no expression in squamous papillary craniopharyngioma. In ACP, Bmp2 was expressed primarily in the stellate reticulum and whorl-like array cells; Runx2 and Osterix tended to be expressed in calcification-related epithelia, including whorl-like array cells and epithelia in/around wet keratin and calcification lesions.

CONCLUSIONS

Our study indicated, for the first time, that osteogenic factor Bmp2 may play an important role in the calcification of ACP via autocrine or paracrine mechanisms. Given the presence of osteogenic markers (Runx2 and Osterix), craniopharyngioma cells could differentiate into an osteoblast-like lineage, and the process of craniopharyngioma calcification resembles that which occurs in osteogenesis/odontogenesis.

High-dose rhBMP-2 for adults: major and minor complications: a study of 502 spine cases

BACKGROUND

Use of recombinant human bone morphogenetic protein-2 (rhBMP-2) has increased considerably since its introduction in 2002. The complications associated with high-dose rhBMP-2 (≥ 40 mg) are unknown. The purpose of our study was to determine outcomes and medical and surgical complications associated with high-dose rhBMP-2 at short-term and long-term follow-up evaluations.

METHODS

Five hundred and two consecutive adult patients who had received high-dose rhBMP-2 as a part of spinal surgery from 2002 to 2009 at one institution were enrolled. Data were entered prospectively and studied and analyzed retrospectively. Surgical procedures in the thoracic and lumbar spine were included. Major and minor complications were documented intraoperatively, perioperatively, and at the latest follow-up examination. Complications potentially associated with rhBMP-2 use were evaluated for correlation with rhBMP-2 dose. Scoliosis Research Society (SRS) and Oswestry Disability Index (ODI) outcome measures were obtained before and after surgery.

RESULTS

On average, 115 mg (range, 40 to 351 mg) of rhBMP-2 was used. The average age of the patients (410 women and ninety-two men) at the time of the index procedure was 52.4 years (range, eighteen to eighty years). There were 265 primary and 237 revision procedures, and 261 patients had interbody fusion. An average of 11.5 vertebrae were instrumented. The average duration of follow-up was forty-two months (range, fourteen to ninety-two months). The diagnoses included idiopathic scoliosis (41%), degenerative scoliosis (31%), fixed sagittal imbalance (18%), and other diagnoses (10%). The rate of intraoperative complications was 8.2%. The rate of perioperative major surgical complications was 11.6%. The rate of perioperative major medical complications was 11.6%. Minor medical complications occurred in 18.9% of the cases, and minor surgical complications occurred in 2.6%. Logistic regression analysis and Pearson correlation did not identify a significant correlation between rhBMP-2 dosage and radiculopathy (r = -0.006), seroma (r = -0.003), or cancer (r = -0.05). Significant improvements in the ODI score (from a mean of 41 points to a mean of 26 points; p < 0.001) and the SRS total score (from a mean of 3.0 points to a mean of 3.7 points; p < 0.001) were noted at the latest follow-up evaluation.

CONCLUSIONS

This is the largest study of which we are aware that examines complications associated with high-dose rhBMP-2. Major surgical complications occurred in 11.6% of patients, and 11.6% experienced major medical complications. There was a cancer prevalence of 3.4%, but no correlation between increasing rhBMP-2 dosage and cancer, radiculopathy (seen in 1% of the patients), or seroma (seen in 0.6%) was found.

Effects of bioactive glass S53P4 or beta-tricalcium phosphate and bone morphogenetic protein-2 and bone morphogenetic protein-7 on osteogenic differentiation of human adipose stem cells

The effects of bioactive glass S53P4 or beta-tricalcium phosphate; and bone morphogenetic proteins bone morphogenetic protein-2, bone morphogenetic protein-7, or bone morphogenetic protein-2 + 7 on osteogenic differentiation of human adipose stem cells were compared in control medium, osteogenic medium, and bone morphogenetic protein-supplemented osteogenic medium to assess suitability for bone tissue engineering. Cell amount was evaluated with qDNA measurements; osteogenic differentiation using marker gene expression, alkaline phosphate activity, and angiogenic potential was measured by vascular endothelial growth factor expression. As compared to beta-tricalcium phosphate, cell amount was significantly greater for bioactive glass in control medium after 7 days and in osteogenic medium after 14 days, and alkaline phosphate activity was always significantly greater for bioactive glass in control medium. However, alkaline phosphate activity increased for beta-tricalcium phosphate and decreased for bioactive glass granules in osteogenic medium. For both biomaterials, bone morphogenetic protein supplementation decreased cell amount and osteogenic differentiation of human adipose stem cells, and vascular endothelial growth factor expressions correlated with cell amounts. Effects of culture medium on human adipose stem cells are biomaterial dependent; bioactive glass in control medium enhanced osteogenic differentiation most effectively.

Engineering axially vascularized bone in the sheep arteriovenous-loop model

Treatment of complex bone defects in which vascular supply is insufficient is still a challenge. To overcome the limitations from autologous grafts, a sheep model has been established recently, which is characterized by the development of an independent axial vascularization of a bioartificial construct, permitting microsurgical transplantation. To engineer independently axially vascularized bone tissue in the sheep arteriovenous (AV)-loop model, mesenchymal stem cells (MSCs), without and in combination with recombinant human bone morphogenetic protein-2 (rhBMP-2), were harvested and directly autotransplanted in combination with β-tricalcium phosphate-hydroxyapatite (β-TCP-HA) granules into sheep in this study. After explantation after 12 weeks, histological and immunohistochemical evaluation revealed newly formed bone in both groups. An increased amount of bone area was obtained using directly autotransplanted MSCs with rhBMP-2 stimulation. Osteoblastic and osteoclastic cells were detected adjacent to the newly formed bone, revealing an active bone remodelling process. Directly autotransplanted MSCs can be found close to the β-TCP-HA granules and are contributing to bone formation. Over time, magnetic resonance imaging (MRI) and micro-computed tomography (μCT) imaging confirmed the dense vascularization arising from the AV-loop. This study shows de novo engineering of independently axially vascularized transplantable bone tissue in clinically significant amounts, using directly autotransplanted MSCs and rhBMP-2 stimulation in about 12 weeks in the sheep AV-loop model. This strategy of engineering vascularized transplantable bone tissue could be possibly transferred to the clinic in the future in order to augment current reconstructive strategies.

Use of recombinant bone morphogenetic protein 2 in free flap reconstruction for osteonecrosis of the mandible

PURPOSE

Osteoradionecrosis of the mandible is a debilitating consequence of radiation therapy for head-and-neck malignancy. It can result in pain, bone exposure, fistula formation, and pathologic fracture. Recombinant human bone morphogenetic protein 2 (rhBMP-2) has shown promise in reconstruction of bone defects. The purpose of this study is to determine whether the addition of rhBMP-2 at the union of vascularized bone and native bone improves surgical outcomes in patients with osteonecrosis of the mandible.

MATERIALS AND METHODS

This study was a retrospective analysis of patients who were treated between 2006 and 2010 for osteonecrosis of the mandible. Patients requiring definitive reconstruction after failure of a course of conservative management were included. Patients were divided into 2 cohorts depending on whether rhBMP-2 was used during the reconstruction. The primary outcome measure was defined as stable mandibular union.

RESULTS

Seventeen patients were included. The development of malunion was similar in both groups (13% for rhBMP-2 group vs 11% for non-rhBMP-2 group). Infectious complications were similar between the groups (25% in rhBMP-2 group vs 56% in non-rhBMP-2 group, P = .33). The rates of hardware removal were similar for the 2 groups (33% in non-rhBMP-2 group vs 25% in rhBMP-2 group, P = .10). No cancer recurrences were observed in patients receiving rhBMP-2.

CONCLUSIONS

The use of rhBMP-2 is safe in free flap reconstruction of the mandible, but its ability to significantly improve patient outcomes, as measured by rates of malunion, reoperation, or infection, is still unknown.

rhBMP-2 has adverse effects on human oral carcinoma cell lines in vivo

OBJECTIVES/HYPOTHESIS

To establish the relevance of the bone morphogenetic protein (BMP) signaling pathway in human oral squamous cell carcinoma (OSCCA) cell lines and determine if there is a biologic impact of stimulating this pathway with recombinant human (rh) BMP-2.

STUDY DESIGN

In vitro laboratory investigations and in vivo analysis using an orthotopic animal model for oral cancer.

METHODS

Gene expression profiles for BMP-2 and components of the BMP-signaling pathway were determined using reverse transcriptase-polymerase chain reaction. In vivo effects were evaluated using Kaplan-Meier survival analysis and studying histopathologic changes in established tumor xenografts with or without rhBMP-2 pretreatment. A phosphokinase array was used to detect levels of activation in signaling kinases.

RESULTS

The BMP-2 gene was expressed in 90% of the 30 OSCCA cell lines tested. Gene expression of all components of the BMP-signaling pathway was highly conserved. Tumor xenografts established with rhBMP-2-treated cells showed more rapid local growth that resulted in worse animal survival as compared to the control group. These tumors had a more poorly differentiated morphology. Changes in protein kinases suggested interactions of BMP-2 signaling with the Wnt-β-catenin, and Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathways.

CONCLUSIONS

Human OSCCA cell lines frequently express BMP-2 and all necessary components of the BMP-signaling pathway. Exogenous treatment of human OSCCA cell lines with rhBMP-2 prior to engraftment in an orthotopic animal model caused the subsequent tumors to be more locally aggressive with worse survival. Continued caution should be used for considering rhBMP-2 for reconstruction of bone defects in oral cancer patients.

Treatment effects of rhBMP-2 on invasiveness of oral carcinoma cell lines

OBJECTIVE

To determine if recombinant human bone morphogenetic protein-2 (rhBMP-2) has biological effects on the invasiveness of human oral squamous cell carcinoma (OSCCA) cell lines.

STUDY DESIGN

Laboratory investigation using six human OSCCA cell lines, with three cell lines having baseline gene expression of BMP-2 and three cell lines without baseline gene expression of BMP-2.

METHODS

The invasiveness of each cell line was measured using a matrigel invasion assay with or without stimulation by rhBMP-2. A tumor metastasis quantitative PCR array was used to establish whether observed findings from the invasion assay correlated to changes in gene expression.

RESULTS

There was a significant increase in tumor cell invasion in response to rhBMP-2 in all BMP-2 positive cell lines but no change in the cell lines that did not express the BMP-2 gene. Quantitative PCR revealed that changes in gene expression were distinctly different based on the baseline gene expression of BMP-2 and favored a more metastatic genotype in the BMP-2-positive cells.

CONCLUSIONS

Recombinant human BMP-2 has an adverse biological effect on invasiveness of human OSCCA cell lines in vitro. This adverse effect is dependent on the baseline gene expression of BMP-2. Changes in expression of genes involved with tumor metastasis correlated to the invasion assay findings. These data raise concern for the safe application of rhBMP-2 for reconstruction of bone defects in oral cancer patients.