Wednesday, April 29, 2009


Thalidomide affects the skeletal system of young rats.

"The experiments were carried out on 5-week-old male Wistar rats. The animals were administered thalidomide in the doses of 15, 30 or 60 mg/kg p.o. over the period of 1, 3 or 6 weeks. The body mass gain, bone mass in the tibia, femur and L-4 vertebra, histomorphometric parameters of the femur (width of trabeculae, width of epiphyseal cartilage, the transverse cross-sectional area of the bone marrow cavity and the cortical bone) and the tibia (width of osteoid, diaphysis transverse growth, the transverse cross-sectional area of the bone marrow cavity and the cortical bone) were studied. The investigations carried out provide, for the first time, information concerning the influence of thalidomide upon bone remodeling processes in young rats. The effects of thalidomide on the skeletal system of young rats depended on the dose and upon application time. After administration of doses 15, 30 and 60 mg/kg p.o. for 1 and 3 weeks, no influence of thalidomide was noted upon the examined macrometric parameters and histomorphometric parameters of femur, tibia and L-4 vertebra in young rats. Significant disturbances of bone remodeling in young rats have been observed after 6 weeks of thalidomide application, while the progression of those changes increased with the increase of the dose administered. After administering the dose of 15 mg/kg p.o. for the period of 6 weeks, no significant changes were found, as regards the macrometric and histomorphometric parameters of bones. Thalidomide, applied 6 weeks in the dose of 30 mg/kg p.o., and in particular in the dose of 60 mg/kg p.o., turned out to disturb bone remodeling processes. In animals administered thalidomide in the dose of 60 mg/kg p.o., reduction mass of tibia, femur, and L-4 vertebra has been observed. In compact bone, thalidomide reduced the diaphysis transverse growth of tibia, reduced the width of osteoid, as well as reduced the transverse cross-sectional area of cortical bone, increased the transverse cross-sectional area of marrow cavity, and increased the transverse cross-sectional area of the marrow cavity/transverse cross-sectional area of the diaphysis ratio of tibia and femur. In cancellous bone, thalidomide reduced the width of bone trabeculae, and increased the width of epiphyseal cartilage. Thalidomide applied for 6 weeks in the dose of 60 mg/kg p.o. inhibited the bone formation processes and increased the bone resorption in young rats."

"The anti-inflammatory action of thalidomide is related to the inhibition of synthesis and release of pro-inflammatory cytokines, mainly tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1) and interleukin-6 (IL-6)"

Thalidomide stimulates lymphocyte activity and production.

"Thalidomide exerts direct anti-proliferative effect, as a result of inhibiting the growth of neoplastic cells in the G1 phase of cell cycle"

Thalidomide dose-demendently decreased femur and tibia length from 15-60 mg/kg.

Saturday, April 25, 2009


Local inhibition of 5-lipoxygenase enhances bone formation in a rat model.

"decreasing 5-lipoxygenase (5-LO) activity during fracture healing increases cyclooxygenase-2 (COX-2) expression in the fracture callus, accelerates chondrogenesis and decreases healing time.
Bilateral, unicortical femoral defects were used in rats. The defect sites were filled with a polycaprolactone (PCL) scaffold containing 5-LO inhibitor (A-79175) at three dose levels, scaffold with drug carrier, or scaffold only. Drug release was assessed in vitro. Osteogenesis was assessed by micro-CT and histology at two endpoints of ten and 30 days.
A-79175, a 5-LO inhibitor, increased bone formation in an apparent dose-related manner."

"The principal function of 5-LO is to convert arachidonic acid into leukotriene A4, which is used to synthesise leukotriene B4 (LTB4) and the cysteinyl leukotrienes. LTB4 and the cysteinyl leukotrienes are lipid signalling molecules that affect many physiological processes, including inflammation, which is an early physiological response to fracture. Arachidonic acid is also the substrate for cyclooxygenase-1 and cyclooxygenase-2 (COX-2), which convert arachidonic acid into prostaglandin (PG)-H2. PGH2 is used to synthesise thromboxane A2, PGD2, PGE2, PGF2α, and PGI2."

"reduced 5-LO activity was associated with enhanced fracture healing, including elevated callus chondrogenesis, increased bone formation and elevated COX-2 expression."

Fig. 3
The control group actually seems to have more cartilage.


Altered bone development and turnover in transgenic mice over-expressing lipocalin-2 in bone.

"LCN2[Lipocalin-2] was expressed during osteoblast differentiation and we generated transgenic (Tg) mice over-expressing LCN2{under the Col1a1 promoter} in bone. Tg mice were smaller and presented bone microarchitectural changes in both endochondral and intramembranous bones. In particular, Tg bones displayed a thinner layer of cortical bone and a decreased trabecular number. Osteoblast bone matrix deposition was reduced and osteoblast differentiation was slowed-down. Differences were also observed in the growth plate of young transgenic mice where chondrocyte displayed a more immature phenotype and a lower proliferation rate. In bone marrow cell cultures from transgenic mice, the number of osteoclast progenitors was increased whereas in vivo it was increased the number of mature osteoclasts expressing tartrate resistant acid phosphatase (TRAP). Finally, while osteoprotegerin (OPG) levels remained unchanged, the expression of the conventional Receptor Activator of Nuclear factor-κB Ligand (RANKL) and of the IL-6 was enhanced in Tg mice."

Would decreasing LCN2 levels increase height?

"LCN2 binds iron influencing cellular proliferation rate."<-Maybe increasing the levels of iron can counteract high LCN2 levels?

"When added to cultures of the ATDC5 cell line, [LCN2] affected chondrocyte proliferation and differentiation"

"Both Lcn2 mRNA and protein expression were negligible in undifferentiated cells (T0)"

Femur length in transgenic mice was shorter than wild type starting at three weeks.  In transgenic mice there was higher staining for Type II Collagen and lower staining for Type X collagen.

"LCN2 is expressed in chondrocytes during endochondral ossification"

"bones of Tg mice grew at a slower rate than Wt bones."<-So only rate may have been affected and not adult height.

"transgenic mice over-expressing IL-6 were smaller"

According to Lipocalin 2 deficiency dysregulates iron homeostasis and exacerbates endotoxin-induced sepsis., LCN2 KO mice have higher levels of iron.

LCN2 is a gene that is likely required to be at optimal levels for maximal height growth.

Wednesday, April 22, 2009


The ciliary Evc/Evc2 complex interacts with Smo and controls Hedgehog pathway activity in chondrocytes by regulating Sufu/Gli3 dissociation and Gli3 trafficking in primary cilia.

"Mutations in EVC or EVC2 disrupt Hh signaling in tooth and bone development. Using mouse models, we show here that Evc and Evc2 are mutually required for localizing to primary cilia and also for maintaining their normal protein levels. Consistent with Evc and Evc2 functioning as a complex, the skeletal phenotypes in either single or double homozygous mutant mice are virtually indistinguishable. Smo translocation to the cilium was normal in Evc2-deficient chondrocytes following Hh activation with the Smo-agonist SAG. However, Gli3 recruitment to cilia tips was reduced and Sufu/Gli3 dissociation was impaired. Interestingly, we found Smo to co-precipitate with Evc/Evc2, indicating that in some cells Hh signaling requires direct interaction of Smo with the Evc/Evc2 complex. Expression of a dominantly acting Evc2 mutation previously identified in Weyer's acrodental dysostosis (Evc2Δ43) caused mislocalization of Evc/Evc2Δ43 within the cilium and also reproduced the Gli3-related molecular defects observed in Evc2(-/-) chondrocytes. Moreover, Evc silencing in Sufu(-/-) cells attenuated the output of the Hh pathway, suggesting that Evc/Evc2 also promote Hh signaling in the absence of Sufu. The Hh pathway involves Evc/Evc2-dependent modulations that are necessary for normal endochondral bone formation."

"Whole-mount alcian blue–alizarin red staining in newborn pups showed the Evc2 knockouts with progressive proximodistal shortening of the limbs, short ribs and morphological defects in the frontal region of the cranial base, hence reproducing the gross phenotype of Evc−/− mice"

"the Evc2−/− growth plates showed reduced regions of proliferating and hypertrophic chondrocytes, decreased expression of Ihh targets"

"Hh signaling is reduced when Evc/Evc2 are distributed along the cilium following simultaneous overexpression of both wild-type proteins or in the presence of mutant Weyers-complexes (Evc/Evc2Δ43), which also bind Smo. "


SDF-1 promotes endochondral bone repair during fracture healing at the traumatic brain injury condition.

"The objective of this study was to investigate the role of stromal cell-derived factor-1 (SDF-1) and its receptor, CXCR4, on bone healing and whether SDF-1 contributes to accelerating bone repair in traumatic brain injury (TBI)/fracture model.
Real-time polymerase chain reaction and immunohistochemical analysis were used to detect the expression of SDF-1 during the repair of femoral bone in TBI/fracture model. The TBI/fracture model was treated with anti-SDF-1 neutralizing antibody or AMD3100, an antagonist for CXCR4, and evaluated by histomorphometry. In vitro and in vivo migration assays were used to evaluate the functional effect of SDF-1 on primary mesenchymal stem cells.
The expression of SDF1 and CXCR4 messenger RNA was increased during the bone healing in TBI/fracture model but was less increased in fracture only model. High expression of SDF-1 protein was observed in the surrounding tissue of the damaged bone. Treated with anti-SDF-1 antibody or AMD3100 could inhibit new bone formation. SDF-1 increased mesenchymal stem cell chemotaxis[cell movement] in vitro in a dose-dependent manner. The in vivo migration study demonstrated that mesenchymal stem cells recruited by SDF-1 participate in endochondral bone repair."

"patients with TBI possess a humoral mechanism for enhanced fracture-healing and that the serum of patients with brain injuries was able to promote the osteoblastic mitosis and multiplication in rats in a dose dependent manner"<-the brain may inhibit growth.

"SDF-1 is expressed at the endosteum and the growth plate of normal long bones in adults"

"the percentage of BrdU-positive chondrocytes in the endochondral callus was 27.6%, demonstrating that the migrated cells had differentiated into chondrocytes."<-BrdU refers to the number of replicating cells.  So a large nuumber of migrating cells were responsible for the callus.  So for height we either have to increase migration or increase mesenchymal stem cell proliferation.


Constitutive activation of Gli2 impairs bone formation in postnatal growing mice.

"the Gli2 transcription activator critically mediates Ihh function in osteoblastogenesis. To explore the possibility that activation of Hedgehog (Hh) signaling may enhance bone formation, we generated mice that expressed a constitutively active form of Gli2 in the Osx-lineage cells. Unexpectedly, these mice exhibited severe osteopenia due to a marked decrease in osteoblast number and function, although bone resorption was not affected.  Osteoblast differentiation was impaired in the mutant mouse. However, the osteoblast-lineage cells isolated from these mice exhibited more robust osteoblast differentiation than normal in vitro. Similarly, pharmacological stimulation of Hh signaling enhanced osteoblast differentiation from Osx-expressing cells isolated from the wild-type mouse. Thus, even though Hh signaling directly promotes osteoblast differentiation in vitro, constitutive activation of this pathway impairs bone formation in vivo, perhaps through an indirect mechanism."

"OsxΔNGli2 mice of either sex possessed shorter long bones than either wild type or Osx-Cre sex-matched counterparts"

Saturday, April 18, 2009


The Role of Fetuin-A in Physiological and Pathological Mineralization

"A prototypic systemic inhibitor protein of mineralization [is] the hepatic plasma protein α2-Heremans-Schmid glycoprotein/fetuin-A. Fetuin-A mediates the formation of stable colloidal mineral–protein complexes called calciprotein particles (CPPs). Thus, fetuin-A is important in the stabilization and clearance of amorphous mineral precursor phases. Efficient clearance of CPPs and, thus, of excess mineral from circulation prevents local buildup of mineral and calcification of soft tissue. Besides calcium phosphate binding, fetuin-A also acts as a carrier for lipids, which may influence calcification, inflammation, and apoptosis. Fetuin-A-deficient (Ahsg −/−) mice show impaired growth of their long bones and premature growth plate closure. We posit that the absence of fetuin-A in the growth plate causes simultaneous lack of calcification inhibition and excess lipid hormone signaling, leading to premature growth plate mineralization and shortened long bones. Fetuin-A regulates endochondral ossification through mineralization inhibition and lipid (hormone) binding."

But can excessive amounts of Fetuin-A increase height?

"Fetuin-A inhibits trypsin"<-Fetuin-A also antagonizes(decreases) TGF-Beta signaling.

"In addition to an increased risk of ectopic calcification, Ahsg −/− mice have stunted femoral bones as well as increased cortical thickness and mechanical stability of these bones. This suggests a role for fetuin-A in endochondral bone formation beyond the established role in calcification inhibition"

"The growth plates of Ahsg −/− mice were disorganized, the number of chondrocyte columns was reduced, and unmineralized cartilage islands were present in the metaphysis."

Overexpression of fetuin-a counteracts ectopic mineralization in a mouse model of pseudoxanthoma elasticum (abcc6(-/-)).

"overexpression of fetuin-A in Abcc6(-/-) mice counteracts the ectopic mineralization. Delivery of an expression construct containing full-length mouse fetuin-A complementary DNA (cDNA), linked to a His-tag, to the liver of these mice resulted in elevated serum levels of this protein. As a consequence, soft tissue mineralization, which is a characteristic of Abcc6(-/-) mice, was reduced by approximately 70% at 12 weeks of age, but the effect was transient when examined 4 weeks later."

Unfortunately, no length data was obtained.

Fetuin-A and change in body composition in older persons.

Men and women aged 70-79 were studied.

Change in height after 5 years was "was −0.2 ± 2 cm"

Height data was measured but it's relationship to Fetuin-A was not presented :(

Fetuin A is also known as Alpha 2-HS-glycoprotein.

Alpha 2-HS-glycoprotein: expression in chondrocytes and augmentation of alkaline phosphatase and phospholipase A2 activity.

"The concentration of alpha 2-HS-glycoprotein dynamically changes in various physiological conditions and is highest in bone during growth. mRNA transcripts from growth zone and resting zone costochondral chondrocyte cultures hybridized with alpha 2-HS-glycoprotein cDNA. However, a difference of mRNA transcript size was observed, with chondrocyte mRNA transcripts being 2.2 kb, while mRNA isolated from liver was 1.6 kb. Presence of alpha 2-HS-glycoprotein in cartilage cells was found by immunohistochemical staining of human fetal epiphyses using anti-human alpha 2-HS-glycoprotein antibody. To understand the role of alpha 2-HS-glycoprotein in cartilage growth, the effects of exogenous alpha 2-HS-glycoprotein were correlated with alkaline phosphatase (ALPase) and phospholipase A2 (PA2) activity in the chondrocyte cultures. Alkaline phosphatase specific activity was stimulated by alpha 2-HS-glycoprotein at concentrations between 0.25 and 1.25 micrograms/mL in the growth zone and resting zone cultures 2.7 and 2.0-fold, respectively. Matrix vesicle PA2 activity was increased only in the growth zone chondrocyte cultures. These results suggested that alpha 2-HS-glycoprotein may contribute to the regulation of the expression of the chondrocyte phenotype. Steady state mRNA levels of ALPase were analyzed in chondrocytes after additions of alpha 2-HS-glycoprotein. The ALPase mRNA levels remained stationary during the stimulation of enzymatic activity, indicating that the effect of alpha 2-HS-glycoprotein upon alkaline phosphatase activity is not at the transcriptional level."

Couldn't connect to this study right now.

Wednesday, April 8, 2009


Deficiency of the Cyclin-Dependent Kinase Inhibitor, CDKN1B, Results in Overgrowth and Neurodevelopmental Delay.

"Germline mutations in the cyclin-dependent kinase inhibitor, CDKN1B, have been described in patients with multiple endocrine neoplasia (MEN), a cancer predisposition syndrome with adult onset neoplasia and no additional phenotypes. Here, we describe the first human case of CDKN1B deficiency, which recapitulates features of the murine CDKN1B knockout mouse model, including gigantism and neurodevelopmental defects. Decreased mRNA and protein expression of CDKN1B were confirmed in the proband's peripheral blood, which is not seen in MEN syndrome patients. We ascribed the decreased protein level to a maternally derived deletion on chromosome 12p13 encompassing the CDKN1B locus (which reduced mRNA expression) and a de novo allelic variant (c.-73G>A) in the CDKN1B promoter (which reduced protein translation)."

"The p27-/- mouse exhibits gigantism and hyperplasia of multiple organs including
the brain"

"the effect of p27 absence and gigantism [is due] to increased Sox2 levels, as p27 directly inhibits Sox2 expression"

"In p27-/- mice, the gigantism was due to Sox2-dependent increase in thickness of the pituitary progenitor layer."

"Germline heterozygote mutations in human CDKN1C are related to Beckwith-Wiedemann Syndrome, which is associated with overgrowth, developmental delay and tumour predisposition"

Saturday, April 4, 2009


Plasminogen plays a crucial role in bone repair.

"we investigated bone repair and ectopic bone formation using plasminogen deficient (Plg-/- ) mice. Bone repair of the femur is delayed in Plg-/- mice, unlike that in the wild-type (Plg+/+ ) mice. The deposition of cartilage matrix and osteoblast formation were both decreased in Plg-/- mice. Vessel formation, macrophage accumulation, and the levels of vascular endothelial growth factor (VEGF) and transforming growth factor-β (TGF-β) were decreased at the site of bone damage in Plg-/- mice. Conversely, heterotopic ossification was not significantly different between Plg+/+ and Plg-/- mice. Moreover, angiogenesis, macrophage accumulation, and the levels of VEGF and TGF-β were comparable between Plg+/+ and Plg-/- mice in heterotopic ossification.  Plasminogen contributes to angiogenesis related to macrophage accumulation, TGF-β, and VEGF, thereby leading to the enhancement of bone repair. "

"In plasminogen-deficient mice, we showed that bone metabolism is regulated by plasminogen/plasmin through the expression of osteoprotegerin, a decoy receptor for receptor activator of NF-κB (RANK) ligand, in osteoblastic cells, and the increase in the number of

"The levels of type II and X collagens in the damaged femur of Plg−/− mice were decreased as compared with Plg+/+ mice"

"chondrogenesis is impaired by plasminogen deficiency during bone repair."<-Does plasminogen help chondrogenesis in conditions other than bone repair?

"The phosphorylation of Smad2/3 in the damaged femur of Plg−/− mice was decreased as compared with Plg+/+ mice"

"angiogenesis is suppressed by plasminogen deficiency, presumably through a reduction of TGF-β, rather than by decreased levels of BMP-2 and HIF-1α."

"local treatment of VEGF reversed delayed bone repair by plasminogen deficiency"

"plasminogen deficiency does not affect BMP-2-induced heterotopic ossification"

"plasminogen deficiency decreases angiogenesis as well as the accumulation of macrophages at the damaged site during bone repair"


Krüppel-like factor 4 regulates membranous and endochondral ossification.

"Klf4 is expressed in the developing flat bones but its expression diminishes postnatally. In the developing long bones, Klf4 is expressed in the perichondrium, trabecular osteoblasts and prehypertrophic chondrocytes. In contrast, osteoblasts lining at the surface of the bone collar showed extremely low levels of Klf4 expression. To investigate the possible roles played by Klf4 during skeletal development, we generated transgenic mice expressing Klf4 under mouse type I collagen regulatory sequence. Transgenic mice exhibited severe skeletal deformities and died soon after birth. Transgenic mice showed delayed formation of the calvarial bones; and over-expressing Klf4 in primary mouse calvarial osteoblasts in culture resulted in strong repression of mineralization indicating that this regulation of Klf4 is through an osteoblast-autonomous effect. Surprisingly, long bones of the transgenic mice exhibited delayed marrow cavity formation. Even at E18.5, the presumptive marrow space was occupied by cartilage anlage and invasion of the vascular endothelial cells and osteoclasts were seldom observed. Instead of entering the cartilage anlage, osteoclasts accumulated at the periosteum in the transgenic mice. Significantly, osteocalcin, which is known to chemotact osteoclasts, was up-regulated at the perichindrium as early as E14.5 in the mutants. In vitro studies showed that this induction of osteocalcin by Klf4 was regulated at its transcriptional level. Klf4 regulates normal skeletal development through coordinating the differentiation and migration of osteoblasts, chondrocytes, vascular endothelial cells and osteoclasts."

"Klf4 tends to localize in post-mitotic cells"

"in the long bones, Klf4 is expressed in the osteoprogenitor cells of the perichondrium but not in the periosteum or endosteum at the outer and inner surface of the bone collar."

"The total bone length and mineralized length ratio were both significantly reduced in the mutants at postnatal day 0"

Klf4 overexpression increased Osteocalcin{up} and MGP levels but decreased Osterix levels.  MGP inhibits cartilage mineralization.

"initial chondrogenesis and differentiation was relatively normal in the mutants. However, the formation of the POC is severely delayed in the mutants. The cells within this region did not express Col2a1 and Col10a1, expressed Col1a1 only in a narrow domain, but expressed Osp indicating that the cells were retained at late hypertrophic stage."

Klf4 overexpression decreased MMP9 and MMP13 expression.

Klf4 underexpression has negative effects too so Klf4 is likely one of those genes were optimal expression is optimal for height growth.

Thursday, April 2, 2009


The Transcription Factor FoxC1 Regulates Chondrogenesis Together with Gli2 through Induction of PTHrP

"the mutation of FOXC1 is shown to cause Axenfeld-Rieger syndrome (ARS) in human that is characterized by the anterior segment dysgenesis and diverse skeletal abnormalities. Whole mount in situ hybridization demonstrated evident co-expression of FoxC1 mRNA and Col2a1 in the developing limbs. Overexpression of FoxC1 induced alcian blue-positive chondrogenesis in limb bud cells in microculture. FoxC1 plays a role in chondrogenesis.
To further verify the functional role of FoxC1 in chondrogenesis, we searched for transcriptional target of FoxC1. FoxC1 had no effects on Col2a1 and Sox9 mRNA expression. On the other hand, FoxC1 increased PTHrP mRNA expression in conjunction with promoted chondrogenesis. Moreover, FoxC1 together with Gli2 further up-regulated PTHrP expression. FoxC1 [interacts with] Gli2. FoxC1 [binds directly] to the FoxC1 binding element (CTAAATAAC) in the PTHrP gene promoter. Finally, pathogenic missense mutation (Ile126Met) of FOXC1, which is responsible for ARS, suppressed PTHrP expression induced by IHH. FoxC1 promotes chondrogenesis through directly up-regulating PTHrP expression in collaboration with Gli2."


Runx2 Control Chondrocyte Proliferation through Direct Regulation of Cell Cycle Genes

"we generated mice with a conditional ablation of Runx2 in chondrocyte. Selective deletion of Runx2 in chondrocyte by Col2a-Cre was confirmed with Rosa26-tdTomato mice. Homozygeous mice exhibited developmentally failed endochondral ossification and dies shortly after birth. Chondroprogenitors in the hyaline cartilage of wild type mice showed uni-directional differentiation to hypertrophic chondrocytes. Runx2 deficiency resulted in disruption of chondrocyte differentiation as determined by absence of pre/hypertrophy and Collagen type X expression. To our surprise, chondrocyte proliferation which is an integral component of endochondral ossification was severely impaired. We observed a dramatic decrease (50%) in the total cell number in both proliferative and pre-hypertrophic zones of homozygous mutant compared to wild type. Similar reduction in chondrocyte cell number was noted in hyaline cartilage of trachea. Furthermore, in vivo BrdU labeling confirmed this reduction results from a decreased mitotic activity of chondrocyte. This unique role of Runx2 to enhance chondrocyte proliferation is consistent with the growth failure and primordial dwarfism in mutant mice. To mechanistically understand alteration in chondrocyte proliferation rate, we determined genes associated with cell cycle cascade in the Runx2 null growth plate. Our gene microarray identified 5 genes with reproducible differences in expression levels ranging from 3-50 folds. In Runx2 null chondrocytes Sfn mRNA was upregulated, while expression of Gpr132, c-Myb, cyclin A1, A2 were strongly inhibited. Interestingly, the differentially expressed gene set encompass functional grouping across cell cycle from G1/S phase to cell cycle check points and arrest. To assess if Runx2 directly regulate their transcription, we cloned 2kb promoter of all five genes. Multiple high affinity Runx recognition motifs were noted in these promoters. Chromatin immunoprecipitation revealed that in chondrocytes Runx2 is bound to these sites. Consistent with in vivo promoter occupancy, promoter activity of these genes was enhanced by Runx2. Our results establish for the first time that Runx2 is obligatory for chondrocyte proliferation and regulate cell cycle genes. "