Autologous platelet-rich plasma induces bone formation of tissue-engineered bone with bone marrow mesenchymal stem cells on beta-tricalcium phosphate ceramics

Background

The purpose of the study is to investigate whether autologous platelet-rich plasma (PRP) can serve as bone-inducing factors to provide osteoinduction and improve bone regeneration for tissue-engineered bones fabricated with bone marrow mesenchymal stem cells (MSCs) and beta-tricalcium phosphate (β-TCP) ceramics. The current study will give more insight into the contradictory osteogenic capacity of PRP.

Methods

The concentration of platelets, platelet-derived growth factor-AB (PDGF-AB), and transforming growth factor-β1 (TGF-β1) were measured in PRP and whole blood. Tissue-engineered bones using MSCs on β-TCP scaffolds in combination with autologous PRP were fabricated (PRP group). Controls were established without the use of autologous PRP (non-PRP group). In vitro, the proliferation and osteogenic differentiation of MSCs on fabricated constructs from six rabbits were evaluated with MTT assay, alkaline phosphatase (ALP) activity, and osteocalcin (OC) content measurement after 1, 7, and 14 days of culture. For in vivo study, the segmental defects of radial diaphyses of 12 rabbits from each group were repaired by fabricated constructs. Bone-forming capacity of the implanted constructs was determined by radiographic and histological analysis at 4 and 8 weeks postoperatively.

Results

PRP produced significantly higher concentration of platelets, PDGF-AB, and TGF-β1 than whole blood. In vitro study, MTT assay demonstrated that the MSCs in the presence of autologous PRP exhibited excellent proliferation at each time point. The results of osteogenic capacity detection showed significantly higher levels of synthesis of ALP and OC by the MSCs in combination with autologous PRP after 7 and 14 days of culture. In vivo study, radiographic observation showed that the PRP group produced significantly higher score than the non-PRP group at each time point. For histological evaluation, significantly higher volume of regenerated bone was found in the PRP group when compared with the non-PRP group at each time point.

Conclusions

Our study findings support the osteogenic capacity of autologous PRP. The results indicate that the use of autologous PRP is a simple and effective way to provide osteoinduction and improve bone regeneration for tissue-engineered bone reconstruction.

     

Biomechanical properties of 3D-printed bone scaffolds are improved by treatment with CRFP

Background

One of the major challenges in orthopedics is to develop implants that overcome current postoperative problems such as osteointegration, proper load bearing, and stress shielding. Current implant techniques such as allografts or endoprostheses never reach full bone integration, and the risk of fracture due to stress shielding is a major concern. To overcome this, a novel technique of reverse engineering to create artificial scaffolds was designed and tested. The purpose of the study is to create a new generation of implants that are both biocompatible and biomimetic.

Methods

3D-printed scaffolds based on physiological trabecular bone patterning were printed. MC3T3 cells were cultured on these scaffolds in osteogenic media, with and without the addition of Calcitonin Receptor Fragment Peptide (CRFP) in order to assess bone formation on the surfaces of the scaffolds. Integrity of these cell-seeded bone-coated scaffolds was tested for their mechanical strength.

Results

The results show that cellular proliferation and bone matrix formation are both supported by our 3D-printed scaffolds. The mechanical strength of the scaffolds was enhanced by trabecular patterning in the order of 20% for compression strength and 60% for compressive modulus. Furthermore, cell-seeded trabecular scaffolds modulus increased fourfold when treated with CRFP.

Conclusion

Upon mineralization, the cell-seeded trabecular implants treated with osteo-inductive agents and pretreated with CRFP showed a significant increase in the compressive modulus. This work will lead to creating 3D structures that can be used in the replacement of not only bone segments, but entire bones.

     

Mechanical stimulation enhanced estrogen receptor expression and callus formation in diaphyseal long bone fracture healing in ovariectomy-induced osteoporotic rats

Summary

Estrogen receptor (ER) in ovariectomy-induced osteoporotic fracture was reported to exhibit delayed expression. Mechanical stimulation enhanced ER-α expression in osteoporotic fracture callus at the tissue level. ER was also found to be required for the effectiveness of vibrational mechanical stimulation treatment in osteoporotic fracture healing.

Introduction

Estrogen receptor(ER) is involved in mechanical signal transduction in bone metabolism. Its expression was reported to be delayed in osteoporotic fracture healing. The purpose of this study was to investigate the roles played by ER during osteoporotic fracture healing enhanced with mechanical stimulation.

Methods

Ovariectomy-induced osteoporotic SD rats that received closed femoral fractures were divided into five groups, (i) SHAM, (ii) SHAM-VT, (iii) OVX, (iv) OVX-VT, and (v) OVX-VT-ICI, where VT stands for whole-body vibration treatment and ICI for ER antagonization by ICI 182,780. Callus formation and gene expression were assessed at 2, 4, and 8 weeks postfracture. In vitro osteoblastic differentiation, mineralization, and ER-α expression were assessed.

Results

The delayed ER expression was found to be enhanced by vibration treatment. Callus formation enhancement was shown by callus morphometry and micro-CT analysis. Enhancement effects by vibration were partially abolished when ER was modulated by ICI 182,780, in terms of callus formation capacity at 2–4 weeks and ER gene and protein expression at all time points. In vitro, ER expression in osteoblasts was not enhanced by VT treatment, but osteoblastic differentiation and mineralization were enhanced under estrogen-deprived condition. When osteoblastic cells were modulated by ICI 182,780, enhancement effects of VT were eliminated.

Conclusions

Vibration was able to enhance ER expression in ovariectomy-induced osteoporotic fracture healing. ER was essential in mechanical signal transduction and enhancement in callus formation effects during osteoporotic fracture healing enhanced by vibration. The enhancement of ER-α expression by mechanical stimulation was not likely to be related to the increased expression in osteoblastic cells but rather to the systemic enhancement in recruitment of ER-expressing progenitor cells through increased blood flow and neo-angiogenesis. This finding might explain the observed difference in mechanical sensitivity of osteoporotic fracture to mechanical stimulation.

     

ISSLS PRIZE IN BASIC SCIENCE 2017: Intervertebral disc/bone marrow cross-talk with Modic changes

Study design

Cross-sectional cohort analysis of patients with Modic Changes (MC).

Objective

Our goal was to characterize the molecular and cellular features of MC bone marrow and adjacent discs. We hypothesized that MC associate with biologic cross-talk between discs and bone marrow, the presence of which may have both diagnostic and therapeutic implications.

Background data

MC are vertebral bone marrow lesions that can be a diagnostic indicator for discogenic low back pain. Yet, the pathobiology of MC is largely unknown.

Methods

Patients with Modic type 1 or 2 changes (MC1, MC2) undergoing at least 2-level lumbar interbody fusion with one surgical level having MC and one without MC (control level). Two discs (MC, control) and two bone marrow aspirates (MC, control) were collected per patient. Marrow cellularity was analyzed using flow cytometry. Myelopoietic differentiation potential of bone marrow cells was quantified to gauge marrow function, as was the relative gene expression profiles of the marrow and disc cells. Disc/bone marrow cross-talk was assessed by comparing MC disc/bone marrow features relative to unaffected levels.

Results

Thirteen MC1 and eleven MC2 patients were included. We observed pro-osteoclastic changes in MC2 discs, an inflammatory dysmyelopoiesis with fibrogenic changes in MC1 and MC2 marrow, and up-regulation of neurotrophic receptors in MC1 and MC2 bone marrow and discs.

Conclusion

Our data reveal a fibrogenic and pro-inflammatory cross-talk between MC bone marrow and adjacent discs. This provides insight into the pain generator at MC levels and informs novel therapeutic targets for treatment of MC-associated LBP.

     

Suture anchor fixation strength in osteopenic versus non-osteopenic bone for rotator cuff repair

Introduction

Rotator cuff tears are increasing with age. Does osteopenic bone have an influence on the pullout strength of suture anchors?

Materials and methods

SPIRALOK 5.0 mm (DePuy Mitek), Super Revo 5 mm and UltraSorb (both ConMed Linvatec) suture anchors were tested in six osteopenic and six healthy human cadaveric humeri. Incremental cyclic loading was performed. The ultimate failure load, anchor displacement, and the mode of failure were recorded.

Results

In the non-osteopenic bone group, the absorbable SPIRALOK 5.0 mm achieved a significantly better pullout strength (274 N ± 29 N, mean ± SD) than the titanium anchor Super Revo 5 mm (188 N ± 34 N, mean ± SD), and the tilting anchor UltraSorb (192 N ± 34 N, mean ± SD). In the osteopenic bone group no significant difference in the pullout strength was found. The failure mechanisms, such as anchor pullout, rupture at eyelet, suture breakage and breakage of eyelet, varied between the anchors.

Conclusion

The present study demonstrates that, in osteopenic bone, absorbable suture anchors do not have lower pullout strengths than metal anchors. In normal bone, the bioabsorbable anchor in this study even outperformed the non-absorbable anchor.

     

A histomorphometric study of the cancellous spinal process bone in adolescent idiopathic scoliosis

Purpose

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity with increased risk of osteopenia of unknown etiology. This study examined the dynamic histomorphometry of AIS patients to gain insight into the underlying pathogenesis of bone metabolism changes in AIS.

Methods

Bone histomorphometry of the spinous process of the 12th thoracic vertebra was analyzed in 33 AIS patients and compared to age-matched normative data. Patients were classified into bone turnover subgroups, based on bone formation rate.

Results

Bone volume was subnormal in 67% of AIS patients, but normal in 33%. Bone turnover was high in 76% of the patients, normal in 9%, and low in 15%. Compared to those in the low-turnover group, the high-turnover group patients were taller and had higher TRAP5b values.

Conclusions

Bone histomorphometry indicated that bone fragility and abnormal bone turnover were common in AIS patients. These abnormalities might contribute to the poor bone status and etiology in AIS.

     

Room temperature housing results in premature cancellous bone loss in growing female mice: implications for the mouse as a preclinical model for age-related bone loss

Summary

Room temperature housing (22 °C) results in premature cancellous bone loss in female mice. The bone loss was prevented by housing mice at thermoneutral temperature (32 °C). Thermogenesis differs markedly between mice and humans and mild cold stress induced by standard room temperature housing may introduce an unrecognized confounding variable into preclinical studies.

Introduction

Female mice are often used as preclinical models for osteoporosis but, in contrast to humans, mice exhibit cancellous bone loss during growth. Mice are routinely housed at room temperature (18–23 °C), a strategy that exaggerates physiological differences in thermoregulation between mice (obligatory daily heterotherms) and humans (homeotherms). The purpose of this investigation was to assess whether housing female mice at thermoneutral (temperature range where the basal rate of energy production is at equilibrium with heat loss) alters bone growth, turnover and microarchitecture.

Methods

Growing (4-week-old) female C57BL/6J and C3H/HeJ mice were housed at either 22 or 32 °C for up to 18 weeks.

Results

C57BL/6J mice housed at 22 °C experienced a 62 % cancellous bone loss from the distal femur metaphysis during the interval from 8 to 18 weeks of age and lesser bone loss from the distal femur epiphysis, whereas cancellous and cortical bone mass in 32 °C-housed mice were unchanged or increased. The impact of thermoneutral housing on cancellous bone was not limited to C57BL/6J mice as C3H/HeJ mice exhibited a similar skeletal response. The beneficial effects of thermoneutral housing on cancellous bone were associated with decreased Ucp1 gene expression in brown adipose tissue, increased bone marrow adiposity, higher rates of bone formation, higher expression levels of osteogenic genes and locally decreased bone resorption.

Conclusions

Housing female mice at 22 °C resulted in premature cancellous bone loss. Failure to account for species differences in thermoregulation may seriously confound interpretation of studies utilizing mice as preclinical models for osteoporosis.

     

Osteogenic progenitors in bone marrow aspirates have clinical potential for tibial non-unions healing in diabetic patients

Purpose

There is a significantly higher incidence of delayed unions, non-unions, and increased healing time in diabetic patients compared with non-diabetic patients. Studies suggest that diabetics suffer from deficiencies of pancreatic stem/progenitor cells, and a clinically relevant question arises concerning the availability and functionality of progenitor cells obtained from bone marrow of diabetics for applications in bone repair.

Methods

We have evaluated the cellularity and frequency of osteogenic mesenchymal stem cells (MSCs) in bone marrow from 54 diabetic patients (12 with type 1 and 42 with type 2) with tibial non-unions. These patients were treated with bone marrow MSCs (BM-MSCs) delivered in an autologous bone marrow concentrate (BMC). Clinical outcomes and marrow cellularity were compared to 54 non-diabetic, matched patients with tibial non-unions also treated with BMC.

Results

After adjusting for age and sex, no differences were identified with respect to bone marrow cellularity and MSC number among the diabetic and non-diabetic groups and both groups received approximately the same number of MSCs on average. BMC treatment promoted non-union healing in 41 diabetic patients (76 %) and 49 non-diabetic patients (91 %), but the non-diabetic patients healed more quickly and produced a larger volume of callus.

Conclusion

We recommend that diabetic patients be treated with an increased number of progenitor cells by increasing the bone marrow aspiration volume. We also anticipate a need to extend the time of casting and non-weight bearing for diabetic patients as compared with non-diabetic patients.

     

Wheelchair use and lipophilic statin medications may influence bone loss in chronic spinal cord injury: findings from the FRASCI-bone loss study

Summary

We identified a protective bone effect at the knee with lipophilic statin use in individuals with chronic spinal cord injury. Lipophilic statin users gained bone at the knee compared to non-users and wheelchair users lost bone compared to walkers. Ambulation and or statins may be effective osteogenic interventions in chronic spinal cord injury (SCI).

Introduction

SCI increases the risk of osteoporosis and low-impact fractures, particularly at the knee. However, during the chronic phase of SCI, the natural history and factors associated with longitudinal change in bone density remain poorly characterized. In this study, we prospectively assessed factors associated with change in bone density over a mean of 21 months in 152 men and women with chronic SCI.

Methods

A mixed model procedure with repeated measures was used to assess predictors of change in bone mineral density (PROC MIXED) at the distal femur and proximal tibia. Factors with a p value of <0.10 in the univariate mixed models, as well as factors that were deemed clinically significant (gender, age, and walking status), were assessed in multivariable models. Factors with a p value of ≤0.05 were included in the final model.

Results

We found no association between bone loss and traditional osteoporosis risk factors, including age, gender, body composition, or vitamin D level or status (normal or deficient). In both crude and fully adjusted models, wheelchair users lost bone compared to walkers. Similarly, statin users gained bone compared to nonusers.

Conclusions

The statin finding is supported by reports in the general population where statin use has been associated with a reduction in bone loss and fracture risk. Our results suggest that both walking and statins may be effective osteogenic therapies to mitigate bone loss and prevent osteoporosis in chronic SCI. Our findings also suggest that loss of mechanical loading and/or neuronal factors contribute more to disuse osteoporosis than traditional osteoporosis risk factors.

     

The Role of the Immune Cells in Fracture Healing

Purpose of review

Bone fracture healing is a complex physiological process relying on numerous cell types and signals. Inflammatory factors secreted by immune cells help to control recruitment, proliferation, differentiation, and activation of hematopoietic and mesenchymal cells. Within this review we will discuss the functional role of immune cells as it pertains to bone fracture healing. In doing so, we will outline the cytokines secreted and their effects within the healing fracture callus.

Recent findings

Macrophages have been found to play an important role in fracture healing. These immune cells signal to other cells of the fracture callus, modulating bone healing.

Summary

Cytokines and cellular signals within fracture healing continue to be studied. The findings from this work have helped to reinforce the importance of osteoimmunity in bone fracture healing. Owing to these efforts, immunomodulation is emerging as a potential therapeutic target to improve bone fracture healing.

     

Xanthotoxin prevents bone loss in ovariectomized mice through the inhibition of RANKL-induced osteoclastogenesis

Summary

Xanthotoxin (XAT) is extracted from the seeds of Ammi majus. Here, we reported that XAT has an inhibitory effect on osteoclastogenesis in vitro through the suppression of both receptor activator of nuclear factor-κB ligand (RANKL)-induced ROS generation and Ca²⁺ oscillations. In vivo studies showed that XAT treatment decreases the osteoclast number, prevents bone loss, and restores bone strength in ovariectomized mice.

Introduction

Excessive osteoclast formation and the resultant increase in bone resorption activity are key pathogenic factors of osteoporosis. In the present study, we have investigated the effects of XAT, a natural furanocoumarin, on the RANKL-mediated osteoclastogenesis in vitro and on ovariectomy-mediated bone loss in vivo.

Methods

Cytotoxicity of XAT was evaluated using bone marrow macrophages (BMMs). Osteoclast differentiation, formation, and fusion were assessed using the tartrate-resistant acid phosphatase (TRAP) stain, the actin cytoskeleton and focal adhesion (FAK) stain, and the fusion assay, respectively. Osteoclastic bone resorption was evaluated using the pit formation assay. Reactive oxygen species (ROS) generation and removal were evaluated using dichlorodihydrofluorescein diacetate (DCFH-DA). Ca²⁺ oscillations and their downstream signaling targets were then detected. The ovariectomized (OVX) mouse model was adopted for our in vivo studies.

Results

In vitro assays revealed that XAT inhibited the differentiation, formation, fusion, and bone resorption activity of osteoclasts. The inhibitory effect of XAT on osteoclastogenesis was associated with decreased intracellular ROS generation. XAT treatment also suppressed RANKL-induced Ca²⁺ oscillations and the activation of the resultant downstream calcium-CaMKK/PYK2 signaling. Through these two mechanisms, XAT downregulated the key osteoclastogenic factors nuclear factor of activated T cells c1 (NFATc1) and c-FOS. Our in vivo studies showed that XAT treatment decreases the osteoclast number, prevents bone loss, rescues bone microarchitecture, and restores bone strength in OVX mice.

Conclusion

Our findings indicate that XAT is protective against ovariectomy-mediated bone loss through the inhibition of RANKL-mediated osteoclastogenesis. Therefore, XAT may be considered to be a new therapeutic candidate for treating osteoporosis.

     

Role of Marrow Adipocytes in Regulation of Energy Metabolism and Bone Homeostasis

Purpose of review

The goal of this review is to gain a better understanding of marrow adipocyte development, its regulation of energy, and its characterization responsible for bone homeostasis.

Recent findings

Despite major advances in uncovering the complex association of bone-fat in the marrow, the underlying basic biological process of adipose tissue development, as well as its interaction with bone homeostasis in pathophysiological conditions, is still not well understood.

Summary

This review identifies many pro- and anti-osteogenic factors secreted by adipocytes to play a role in the manipulating the fate of mesenchymal stem cells as well as the osteoblastic activity during bone remodeling. It also addresses the function of adipose tissue capable of negative regulation of the hematopoietic microenvironment to influence the bone quantity and the nature of bone homeostasis.

     

Adiponectin is a predictor of bone mineral density in middle-aged premenopausal women

Summary

Adipose-modulated biochemical signal that explains some of the association between fat mass and bone mineral density (BMD) is adiponectin. The results demonstrated an independent association between adiponectin and BMD, while the influence of adiponectin on bone mineral content is mediated by fat free mass in middle-aged women.

Introduction

Positive association between fat mass (FM) and bone mineral density (BMD) is mediated by biochemical factors.

Methods

The relationship between plasma adiponectin concentration and BMD in 98 sedentary premenopausal women aged 38–49 years with a body mass index range of 20.0–42.1 kg/m² was examined. Different body composition and blood biochemical parameters were measured to adjust for possible confounding variables.

Results

The association between adiponectin and BMD values (total BMD: ß?=??0.919; p?=?0.0001, femoral neck BMD: ß?=??0.925; p?=?0.0001 and lumbar spine BMD: ß?=??0.912; p?=?0.0001) was independent of the influences that measured body composition, hormonal and insulin resistance factors may exert on BMD (p??0.21).

Conclusions

Adiponectin is an independent predictor of BMD, while its independent contribution to the interindividual variance in measured values is only modest. The influence of adiponectin on total BMC is mediated or confounded by FFM in middle-aged premenopausal women.

     

The non-steroidal anti-inflammatory drug diclofenac reduces appearance of osteoblasts in bone defect healing in rats

Introduction

Non-steroidal anti-inflammatory drug (NSAID) is well known to significantly delay fracture healing. Results from in vitro studies implicate an impairment of osteoblast proliferation due to NSAIDs during the initial stages of healing. We studied whether diclofenac, a non-selective NSAID, also impairs appearance of osteoblasts in vivo during the early phase of healing (at 10 days).

Materials and methods

Two defects (Ø 1.1 mm) were drilled within distal femurs of 20 male Wistar rats. Ten rats received diclofenac continuously; the other obtained a placebo until sacrificing at 10 days. Osteoblast proliferation was assessed by cell counting using light microscopy, and bone mineral density (BMD) was measured using pQCT.

Results

Osteoblast counts from the centre of bone defect were significantly reduced in the diclofenac group (median 73.5 ± 8.4 cells/grid) compared to animals fed with placebo (median 171.5 ± 13.9 cells/grid). BMD within the defect showed a significant reduction after diclofenac administration (median 111.5 ± 9.3 mg/cm³) compared to the placebo group (median 177 ± 45.4 mg/cm³).

Conclusion

The reduced appearance of osteoblasts in vivo implicates an inhibiting effect of diclofenac on osteoblasts at a very early level of bone healing. The inhibition of proliferation and migration of osteoblasts, or differentiation from progenitor cells, is implicated in the delay of fracture healing after NSAID application.

     

Distinguishing characteristics of stem cells derived from different anatomical regions of human degenerated intervertebral discs

Introduction

Several types of stem cells have been successfully demonstrated to exist in the human degenerated intervertebral disc (IVD), which is composed of annulus fibrosus (AF), nucleus pulposus (NP) and cartilage endplate (CEP). However, the differences in the biological characteristics among these and bone marrow derived mesenchymal stem cells (BM-MSCs) remain unclear.

Materials and methods

To investigate this issue, cells were harvested from human AF, NP, CEP, and bone marrow, respectively; passage 2 cells were selected using the agarose suspension culture system to obtain stem cell clones. Following expansion in vitro, stem cells from different anatomical regions were compared regarding the morphology, proliferation ability, immunophenotypic expression, and multi-lineage differentiation capacity. In addition, stem cell-alginate bead compositions were constructed for the comparison of DNA and sGAG content.

Results

There were subtle differences regarding cell morphology, but no significant differences in proliferation ability among the four types of stem cells. For the immunophenotypic analysis, all stem cells basically fulfilled the criteria for mesenchymal stem cells (MSCs), which have been published by the International Society for Cellular Therapy (ISCT), with a significant difference in CD105 expression. A comparison of the osteogenic capacities indicated: cartilage endplate-derived stem cells (CESCs) > annulus fibrosus-derived stem cells (AFSCs) > BM-MSCs > nucleus pulposus-derived stem cells (NPSCs). The chondrogenesis difference was similar to osteogenesis. For adipogenesis: BM-MSCs >NPSCs >CESCs >AFSCs. In the stem cell/alginate composition, the CESCs consistently showed the superior chondrogenic potential among all those cell types.

Conclusions

Our data indicated that all the four types of stem cells shared some similar biological properties (regarding shape, proliferation ability and immunophenotypic expression). CESCs, which had the strongest osteogenic and chondrogenic potentials, may serve as excellent seed cells for NP/cartilage or bone tissue engineering.

     

Diagnostic accuracy of various modalities relative to open bone biopsy for detection of long bone posttraumatic osteomyelitis

Background

Long bone posttraumatic osteomyelitis (PTOM) is a relatively common complication following surgical fixation of open fractures. There is a lacking consensus on ideal strategies for diagnostic evaluation of long bone PTOM. While open bone biopsy and culture is considered the ‘gold diagnostic standard,’ its cost and invasiveness are often prohibitive and have prompted the search for alternate diagnostic methods.

Objective

To evaluate the sensitivity and specificity of various diagnostic modalities relative to open bone biopsy and culture for the detection of long bone PTOM.

Design

Retrospective cohort study; Level of Evidence, III.

Setting

Urban Level I trauma center and safety-net institution.

Patients/participants

A consecutive cohort of 159 adult patients presenting with long bone PTOM at our Level I trauma center between January 1, 2004, and December 31, 2013, were retrospectively identified. All included patients fulfilled diagnostic criteria for PTOM (as defined by the Center for Disease Control and Prevention) that involved a long bone (femur, fibula, tibia, humerus, radius, and ulna). Patients with diabetic foot infection, septic arthritis, osteomyelitis of the spine/pelvis/hand, or insufficient medical records were excluded.

Main outcome measurements

Sensitivity and specificity of deep wound culture, soft tissue histopathologic examination, and elevated levels of acute phase reactants [C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and leukocyte count (WBC)] were determined using findings of open bone biopsy and culture as a reference standard.

Results

The most common pathogen isolated on open bone culture was staphylococci, contributing to 89 (57%) of 159 cases of long bone PTOM (p < 0.001). Relative to open bone biopsy and culture as the gold diagnostic standard, soft tissue histopathology demonstrated a sensitivity of 69.8% [95% confidence interval (CI) 53.7–82.3%] and specificity of 38.9% (95% CI 18.3–63.9%) for the detection of long bone PTOM. Deep wound culture exhibited a lower sensitivity of 66.0% (95% CI 56.1–74.8%) and specificity of 28.1% (95% CI 12.9–49.5%), a difference that was statistically significant (p = 0.021). Among inflammatory markers, elevated levels of CRP and ESR were equally sensitive for the detection of PTOM compared to open bone biopsy and culture, while WBC was significantly less sensitive (sensitivity 33.2%; 95% CI 25.3–43.7; p < 0.001).

Conclusion

Soft tissue histopathologic examination and deep wound culture are relatively poor substitutes for the diagnosis of long bone PTOM compared to open bone biopsy and culture. The accurate identification of causative pathogens underlying long bone PTOM is critical for diagnosis and choice of antibiotic treatment. Future studies investigating the use of higher-resolution diagnostic methods are merited.

     

The unexpected presence of iron in bone biopsies of hemodialysis patients

Purpose

Bone biopsy defines classical diseases that constitute the renal osteodystrophy. There is a recent concern regarding other histological findings that are not appreciated by using the turnover, mineralization, and volume (TMV) classification. Iron (Fe) overload has been considered a new challenge and the real significance of the presence of this metal in bones is not completely elucidated. Therefore, the main goal of the current study was to not only to identify bone Fe, but also correlate its presence with demographic, and biochemical characteristics.

Methods

This is a cross-sectional analysis of bone biopsies performed in 604 patients on dialysis from 2010 to 2014 in a tertiary academic Hospital.

Results

Histomorphometric findings revealed the presence of Fe in 29.1%. Fe was associated with higher levels of serum ferritin and serum calcium. No TMV status was related to Fe bone overload.

Conclusion

Our study has highlighted that the presence of Fe in one-third of bone samples has unknown clinical significance. The lack of other contemporary bone biopsy study reporting Fe prevents us from comparison. The findings presented here should be specifically addressed in a future research and will require attention prior to implementation of any clinical guideline. If any proposed treatment, however, would change the bone Fe-related morbidity is undetermined.

     

Vertical bone regeneration using rhBMP-2 and VEGF

Background

Sufficient vertical and lateral bone supply and a competent osteogenic healing process are prerequisities for the successful osseointegration of dental implants in the alveolar bone. Several techniques including autologous bone grafts and guided bone regeneration are applied to improve quality and quantity of bone at the implantation site. Depending on the amount of lacking bone one- or two-stage procedures are required. Vertical bone augmentation has proven to be a challenge particularly in terms of bone volume stability. This study focuses on the three dimensional vertical bone generation in a one stage procedure in vivo. Therefore, a collagenous disc-shaped scaffold (ICBM = Insoluble Collagenous Bone Matrix) containing rhBMP-2 (Bone Morphogenetic Protein-2) and/or VEGF (Vascular Endothelial Growth Factor) was applied around the coronal part of a dental implant during insertion. RhBMP-2 and VEGF released directly at the implantation site were assumed to induce the generation of new vertical bone around the implant.

Methods

One hundred eight titanium implants were inserted into the mandible and the tibia of 12 mini pigs. Four experimental groups were formed: Control group, ICBM, ICBM + BMP-2, and ICBM + BMP-2 + VEGF.After 1, 4 and 12 weeks the animals were sacrificed and bone generation was investigated histologically and histomorphometrically.

Results

After 12 weeks the combination of ICBM + rhBMP2 + VEGF showed significantly more bone volume density (BVD%), a higher vertical bone gain (VBG) and more vertical bone gain around the implant (PVBG) in comparison to the control group.

Conclusion

By using collagenous disc-shaped matrices in combination with rhBMP-2 and VEGF vertical bone can be generated in a one stage procedure without donor site morbidity. The results of the presenting study suggest that the combination of rhBMP-2 and VEGF applied locally by using a collagenous carrier improves vertical bone generation in vivo. Further research is needed to establish whether this technique is applicable in clinical routines.