NELL-1 promotes cartilage regeneration in an in vivo rabbit model

Repair of cartilage due to joint trauma remains challenging due to the poor healing capacity of cartilage and adverse effects related to current growth factor-based strategies. NELL-1 (Nel-like molecule-1; Nel [a protein strongly expressed in neural tissue encoding epidermal growth factor like domain]), a protein first characterized in the context of premature cranial suture fusion, is believed to accelerate differentiation along the osteochondral lineage. We previously demonstrated the ability of NELL-1 protein to maintain the cartilaginous phenotype of explanted rabbit chondrocytes in vitro. Our objective in the current study is to determine whether NELL-1 can affect endogenous chondrocytes in an in vivo cartilage defect model. To generate the implant, NELL-1 was incorporated into chitosan nanoparticles and embedded into alginate hydrogels. These implants were press fit into 3-mm circular osteochondral defects created in the femoral condylar cartilage of 3-month-old New Zealand White rabbits (n=10). Controls included unfilled defects (n=8) and defects filled with phosphate-buffered saline-loaded chitosan nanoparticles embedded in alginate hydrogels (n=8). Rabbits were sacrificed 3 months postimplantation for histological analysis. Defects filled with alginate containing NELL-1 demonstrated significantly improved cartilage regeneration. Remarkably, histology of NELL-1-treated defects closely resembled that of native cartilage, including stronger Alcian blue and Safranin-O staining and increased deposition of type II collagen and absence of the bone markers type I collagen and Runt-related transcription factor 2 (Runx2) as demonstrated by immunohistochemistry. Our results suggest that NELL-1 may produce functional cartilage with properties similar to native cartilage, and is an exciting candidate for tissue engineering-based approaches for treating diverse pathologies of cartilage defects and degeneration.

The Nell-1 growth factor stimulates bone formation by purified human perivascular cells

The search for novel sources of stem cells other than bone marrow mesenchymal stem cells (MSCs) for bone regeneration and repair has been a critical endeavor. We previously established an effective protocol to homogeneously purify human pericytes from multiple fetal and adult tissues, including adipose, bone marrow, skeletal muscle, and pancreas, and identified pericytes as a primitive origin of human MSCs. In the present study, we further characterized the osteogenic potential of purified human pericytes combined with a novel osteoinductive growth factor, Nell-1. Purified pericytes grown on either standard culture ware or human cancellous bone chip (hCBC) scaffolds exhibited robust osteogenic differentiation in vitro. Using a nude mouse muscle pouch model, pericytes formed significant new bone in vivo as compared to scaffold alone (hCBC). Moreover, Nell-1 significantly increased pericyte osteogenic differentiation, both in vitro and in vivo. Interestingly, Nell-1 significantly induced pericyte proliferation and was observed to have pro-angiogenic effects, both in vitro and in vivo. These studies suggest that pericytes are a potential new cell source for future efforts in skeletal regenerative medicine, and that Nell-1 is a candidate growth factor able to induce pericyte osteogenic differentiation.

High doses of bone morphogenetic protein 2 induce structurally abnormal bone and inflammation in vivo

The major Food and Drug Association-approved osteoinductive factors in wide clinical use are bone morphogenetic proteins (BMPs). Although BMPs can promote robust bone formation, they also induce adverse clinical effects, including cyst-like bone formation and significant soft tissue swelling. In this study, we evaluated multiple BMP2 doses in a rat femoral segmental defect model and in a minimally traumatic rat femoral onlay model to determine its dose-dependent effects. Results of our femoral segmental defect model established a low BMP2 concentration range (5 and 10 μg/mL, total dose 0.375 and 0.75 μg in 75 μg total volume) unable to induce defect fusion, a mid-range BMP2 concentration range able to fuse the defect without adverse effects (30 μg/mL, total dose 2.25 μg in 75 μg total volume), and a high BMP2 concentration range (150, 300, and 600 μg/mL, total dose 11.25, 22.5, and 45 μg in 75 μg total volume) able to fuse the defect, but with formation of cyst-like bony shells filled with histologically confirmed adipose tissue. In addition, compared to control, 4 mg/mL BMP2 also induced significant tissue inflammatory infiltrates and exudates in the femoral onlay model that was accompanied by increased numbers of osteoclast-like cells at 3, 7, and 14 days. Overall, we consistently reproduced BMP2 side effects of cyst-like bone and soft tissue swelling using high BMP2 concentration approaching the typical human 1500 μg/mL.

Stability comparison between commercially available mini-implants and a novel design: part 1

OBJECTIVE

To compare mechanical stability among five mini-implant designs--a newly invented design and four commercially available designs that vary by shape and threading; to calculate external surface area of each design using high-resolution micro-computed tomography; and to evaluate the relationship between surface area and stability results.

MATERIALS AND METHODS

The four commercially available mini-implants--single-threaded and cylindrical (SC), single-threaded and tapered (ST), double-threaded and cylindrical (DC), double-threaded and tapered (DT)--and a new implant that is designed to engage mostly in cortical bone with shorter and wider dimensions (N1) were inserted in simulated bone with cortical and trabecular bone layers. The mechanical study consisted of torque measurements and lateral displacement tests. External surface area was computed using a 25-µm micro-CT.

RESULTS

Maximum insertion torque, maximum removal torque, and force levels for displacements were the highest in N1, followed by DT, ST, DC, and SC (α  =  .05). The surface area was largest in DT, followed by N1, ST, DC, and SC. Surface area engaged in cortical bone, however, was the greatest in N1. The surface area of mini-implants had positive correlation with stability.

CONCLUSION

Among commercial designs, both added tapering and double threading improved stability. N1 was the most stable design within this research design. The new design has the potential to be clinically superior; it has enhanced stability and there is diminished risk of endangering nearby anatomic structures during placement and orthodontic treatment, but the design requires refinements to reduce insertion torque to avoid clinical difficulty and patient discomfort.

High- versus low-dose leucovorin in 5-fluorouracil-based oxaliplatin- or irinotecan-containing regimen in metastatic colorectal cancer

e15054

Background: Although leucovorin (LV) is widely used as a modulator of 5-fluorouracil (5-FU) for the chemotherapy of advanced colorectal cancer, the optimal dose has not yet been established. Low-dose LV appears to be as active as high-dose LV in the several studies. So, we tried to compare the efficacy of high-versus low-dose LV in the commonly used palliative chemotherapy regimen. Methods: Between May 2003 and May 2008, 40 patients with metastatic colorectal cancer were randomly treated with high-LV (200mg/m2/i.v.) or low-LV (20mg/m2/i.v.) in 5-FU based oxaliplatin (FOLFOX-4) or irinotecan (FOLFIRI) containing regimen. The primary endpoint of the study was the comparison of response rates and the secondary endpoint was the assessment of survival and tolerability. Results: The response rate was 40% in low-LV group with 2 CR and 6 PR, and 35% in high-LV group with 2 CR and 5 PR, without any significant difference (P = 0.89). The median overall survival was 24.3 months in low-LV group and 25.2 months in high-LV group, with no difference between treatments. Toxicity mainly consisted of gastrointestinal side effects, which were rare and similar in the two groups. Conclusions: In this randomized phase II study, the low and high doses of LV appeared to be equivalent in palliative chemotherapy of metastatic colorectal cancer although large-scale phase III study are necessary.

No significant financial relationships to disclose.

The observation of nonlinear ion cyclotron wave excitation during high-harmonic fast wave heating in the large helical device

A wave detector, a newly designed magnetic probe, is installed in the large helical device (LHD). This wave detector is a 100-turn loop coil with electrostatic shield. Comparing a one-loop coil to this detector, this detector has roughly constant power coupling in the lower frequency range of 40 MHz, and it can easily detect magnetic wave in the frequency of a few megahertz. During high-harmonic fast wave heating, lower frequency waves (<10 MHz) were observed in the LHD for the first time, and for the power density threshold of lower frequency wave excitation (7.5 MHz) the power density of excited pumped wave (38.47 MHz) was approximately -46 dBmHz. These lower frequencies are kept constant for electron density and high energy particle distribution, and these lower frequency waves seem to be ion cyclotron waves caused by nonlinear wave-particle interaction, for example, parametric decay instability.

Topographic distribution area of the infraorbital nerve

The infraorbital nerve (ION) supplies the skin and mucous membranes of the middle portion of the face. This nerve is vulnerable to injury during surgical procedures of mid-face. Severe pain and loss of sense are noted in patients whose infraorbital nerve is either entirely or partially lost after these surgeries. We investigated the distribution area and topography of the ION, about which little is currently known, by dissecting 43 hemifaces of Korean cadavers. The ION produced four main branches, the inferior palpebral, internal nasal, external nasal, and superior labial branches. The inferior palpebral branch was generally bifurcated, giving off a medial and a lateral branch (58.1%). The internal nasal branch ran superior to the depressor septi muscle, along the ala of the nose. It supplied the skin of the philtrum and gave off a terminal branch that supplied the nasal septum and the vestibule of the nose. The external nasal branch was distributed diversely supplying areas between the root and the ala of the nose. The superior labial branch was the largest branch of the ION produced the most subbranches. These subbranches were divided into the medial and lateral branches depending upon the area that they supplied.

Involvement of Na+-Ca2+ exchanger on metabotropic glutamate receptor 1-mediated [Ca2+]i transients in rat cerebellar Purkinje neurons

Cerebellar Purkinje neurons have intracellular regulatory systems including Ca2+-binding proteins, intracellular Ca2+ stores, Ca2+-ATPase and Na+-Ca2+ exchanger (NCX) that keep intracellular Ca2+ concentration ([Ca2+]i) in physiological range. Among these, NCX interacts with AMPA receptors, activation of which induces cerebellar synaptic plasticity. And the activation of metabotropic glutamate receptor 1 (mGluR1) is also involved in the induction of cerebellar long-term depression. The interaction of NCX with mGluR1 is not known yet. Thus, in this study, the functional relationship between NCX and mGluR1 in modulating the [Ca2+]i in rat Purkinje neurons was investigated. The interaction between NCX and mGluR1 in Purkinje neurons was studied by measuring intracellular Ca2+ transients induced by an agonist of group I mGluRs, 3,5-dihydroxyphenylglycine (DHPG). The DHPG-induced Ca2+ transient was significantly reduced by treatments of NCX inhibitors, bepridil and KB-R7943. When cells were pretreated with antisense oligodeoxynucleotides of NCX, the DHPG-induced Ca2+ transient was also inhibited. These results suggest that NCX modulates the activity of mGluR1 in cerebellar Purkinje neurons. Therefore, NCX appears to play an important role in the physiological function of cerebellar Purkinje neurons such as synaptic plasticity.

PGC-1 expression level in human colorectal cancer: A predictor of lymph node metastasis

3616

Background: Previous study showed that the expression of peroxisome proliferator-activated receptor γ (PPARγ) and PPARγ coactivator-1 (PGC-1) was correlated with clinical outcome in breast cancer. However, no published data are available about the biological and clinical significance of PGC-1 in colorectal cancer. Thus, our aim was to explore the expression of PPARγ and PGC-1 in colorectal cancer as well as their association with other clinicopathological features, and to evaluate the role of PPARγ and PGC-1 as a prognostic indicator of colorectal cancer. Methods: We have investigated the presence of PPARγ and PGC-1 in human colorectal cancer tissues and adjacent normal tissues from 108 primary colorectal cancer patients by immunohistochemistry. The correlation between their expression and clinicopathologic features was investigated. Three-year overall survival of patients with different expression of PPARγ and PGC-1 were analyzed by the Kaplan-Meier method. Results: No significant correlation was found between PPARγ expression and age at surgery, gender, histopathologic differentiation, depth of infiltration, relapse, and Dukes’ stage. No significant correlation was found between PGC-1 expression and age at surgery, the histopathologic differentiation, the depth of infiltration, and relapse. However, PGC-1 expression was closely related to Duke’s stage and nodal metastasis (p=0.024 and p=0.020, respectively). Survival analysis showed that the PGC-1-positive group has a reduced overall survival (p=0.0367). Conclusions: Based on our results, PGC-1 may be valuable marker of nodal metastasis and represent a biomarker of poor prognosis in colorectal cancer.

No significant financial relationships to disclose.