A radical switch in clonality reveals a stem cell niche in the epiphyseal growth plate.

Longitudinal bone growth in children is sustained by growth plates, narrow discs of cartilage that provide a continuous supply of chondrocytes for endochondral ossification1. However, it remains unknown how this supply is maintained throughout childhood growth. Chondroprogenitors in the resting zone are thought to be gradually consumed as they supply cells for longitudinal growth1,2, but this model has never been proved. Here, using clonal genetic tracing with multicolour reporters and functional perturbations, we demonstrate that longitudinal growth during the fetal and neonatal periods involves depletion of chondroprogenitors, whereas later in life, coinciding with the formation of the secondary ossification centre, chondroprogenitors acquire the capacity for self-renewal, resulting in the formation of large, stable monoclonal columns of chondrocytes. Simultaneously, chondroprogenitors begin to express stem cell markers and undergo symmetric cell division. Regulation of the pool of self-renewing progenitors involves the hedgehog and mammalian target of rapamycin complex 1 (mTORC1) signalling pathways. Our findings indicate that a stem cell niche develops postnatally in the epiphyseal growth plate, which provides a continuous supply of chondrocytes over a prolonged period.

Lithium rescues cultured rat metatarsals from dexamethasone-induced growth failure.

BACKGROUND: Glucocorticoids are commonly used in children with different chronic diseases. Growth failure represents a so far untreatable undesired side-effect. As lithium chloride (LiCl) is known to induce cell renewal in various tissues, we hypothesized that LiCl may prevent glucocorticoid-induced growth failure. METHODS: We monitored growth of fetal rat metatarsals cultured ex-vivo with dexamethasone and/or LiCl, while molecular mechanisms were explored through RNA sequencing by implementing the differential gene expression and gene set analysis. Quantification of ß-catenin in human growth plate cartilage cultured with dexamethasone and/or LiCl was added for verification. RESULTS: After 14 days of culture, the length of dexamethasone-treated fetal rat metatarsals increased by 1.4 ± 0.2 mm compared to 2.4 ± 0.3 mm in control bones (p < 0.001). The combination of LiCl and dexamethasone led to bone length increase of 1.9 ± 0.3 mm (p < 0.001 vs. dexamethasone alone). By adding lithium, genes for cell cycle and Wnt/ß-catenin, Hedgehog and Notch signaling, were upregulated compared to dexamethasone alone group. CONCLUSIONS: LiCl has the potential to partially rescue from dexamethasone-induced bone growth impairment in an ex vivo model. Transcriptomics identified cell renewal and proliferation as candidates for the underlying mechanisms. Our observations may open up the development of a new treatment strategy for bone growth disorders. IMPACT: LiCl is capable to prevent glucocorticoid-induced growth failure in rat metatarsals in vitro. The accompanying drug-induced transcriptomic changes suggested cell renewal and proliferation as candidate underlying mechanisms. Wnt/beta-catenin pathway could be one of those novel mechanisms.

Humanin is a novel regulator of Hedgehog signaling and prevents glucocorticoid-induced bone growth impairment.

Glucocorticoids (GCs) are frequently used to treat chronic disorders in children, including inflammation and cancer. Prolonged treatment with GCs is well known to impair bone growth, an effect linked to increased apoptosis and suppressed proliferation in growth plate chondrocytes. We hypothesized that the endogenous antiapoptotic protein humanin (HN) may prevent these effects. Interestingly, GC-induced bone growth impairment and chondrocyte apoptosis was prevented in HN overexpressing mice, HN-treated wild-type mice, and in HN-treated cultured rat metatarsal bones. GC-induced suppression of chondrocyte proliferation was also prevented by HN. Furthermore, GC treatment reduced Indian Hedgehog expression in growth plates of wild-type mice but not in HN overexpressing mice or HN-treated wild-type animals. A Hedgehog (Hh) antagonist, vismodegib, was found to suppress the growth of cultured rat metatarsal bones, and this effect was also prevented by HN. Importantly, HN did not interfere with the desired anti-inflammatory effects of GCs. We conclude that HN is a novel regulator of Hh signaling preventing GC-induced bone growth impairment without interfering with desired effects of GCs. Our data may open for clinical studies exploring a new possible strategy to prevent GC-induced bone growth impairment by cotreating with HN.-Zaman, F., Zhao, Y., Celvin, B., Mehta, H. H., Wan, J., Chrysis, D., Ohlsson, C., Fadeel, B., Cohen, P., Sävendahl, L. Humanin is a novel regulator of Hedgehog signaling and prevents glucocorticoid-induced bone growth impairment.

Humanin prevents undesired apoptosis of chondrocytes without interfering with the anti-inflammatory effect of dexamethasone in collagen-induced arthritis.

OBJECTIVES: Prolonged use of glucocorticoids (GCs) for treatment of inflammatory and autoimmune conditions may have several negative side effects, such as impaired bone growth which has been linked to increased apoptosis in growth plate chondrocytes. It has recently been shown that humanin, a small mitochondrial derived peptide, rescues growth plate chondrocytes from GC-induced apoptosis. Our aim was to study if a synthetic analogue of humanin, [Gly14]-HNG (HNG), can be safely used to prevent GC-induced toxicity in growth plate chondrocytes without interfering with the desired anti-inflammatory effect in an in vivo model of arthritis. METHODS: Arthritis was induced in DBA/1 mice by collagen type II in complete Freund's adjuvant and the animals were treated with Dexamethasone (Dexa) (0.25 mg/kg/day) with or without HNG (100 µg/kg/day) for 14 days. The animals were observed daily for the presence of arthritis including signs of erythema and swelling of the joints. The paws were scored based on the severity of the swelling. After termination, histological scoring was performed of all paws. Chondrocyte apoptosis and proliferation were analysed by TUNEL assay and PCNA staining, respectively. RESULTS: We found that HNG treatment in combination with Dexa protected from Dexa-induced chondrocyte apoptosis in both articular and growth plate cartilage. Furthermore, based on clinical and histology scoring analyses, HNG did not interfere with the desired anti-inflammatory effect of Dexa. CONCLUSIONS: Our results suggest that the combination of HNG and GCs may provide a new treatment strategy in conditions of chronic inflammation, which could potentially prevent bone growth impairment.

Growth and Pubertal Timing in Boys With Adult-diagnosed Celiac Disease: A Population-based Longitudinal Cohort Study.

There are few longitudinal data on whether childhood growth and pubertal timing may be impaired by adult-diagnosed celiac disease (CD). Through school health care records and national registers, we retrieved serial growth measurements on 37,672 Swedish boys born in 1945 to 1961, out of whom 72 (0.2%) were clinically diagnosed with CD as adults. Boys with, versus without, adult-diagnosed CD exhibited no appreciable mean differences in body mass index (BMI, kg/m) and height (cm) at ages 8 or 20 to 21 years (childhood BMI, 15.9 [CD] vs 15.7 [comparators]; childhood height, 129.1 [CD] vs 128.6 [comparators]; adult BMI, 21.3 [CD] vs 21.4 [comparators]; adult height, 180.7 [CD] vs 180.4 [comparators]). Neither did we observe any between-group differences in growth development during puberty nor in the timing of pubertal growth spurt (all P values ≥0.30). Conclusively, in this population-based longitudinal study, boys with adult-diagnosed CD had similar growth and pubertal timing as their peers.

Radial Extracorporeal Shock Wave Treatment Promotes Bone Growth and Chondrogenesis in Cultured Fetal Rat Metatarsal Bones.

BACKGROUND: Substantial evidence exists to show the positive effects of radialextracorporeal shock wave therapy (ESWT) on bone formation. However, it is unknown whether rESWT can act locally at the growth plate level to stimulate linear bone growth. One way to achieve this is to stimulate chondrogenesis in the growth plate without depending on circulating systemic growth factors. We wished to see whether rESWT would stimulate metatarsal rat growth plates in the absence of vascularity and associated systemic growth factors. QUESTIONS/PURPOSES: To study the direct effects of rESWT on growth plate chondrogenesis, we asked: (1) Does rESWT stimulate longitudinal bone growth of ex vivo cultured bones? (2) Does rESWT cause any morphological changes in the growth plate? (3) Does rESWT locally activate proteins specific to growth plate chondrogenesis? METHODS: Metatarsal bones from rat fetuses were untreated (controls: n = 15) or exposed to a single application of rESWT at a low dose (500 impulses, 5 Hz, 90 mJ; n = 15), mid-dose (500 impulses, 5 Hz, 120 mJ; n = 14) or high dose (500 impulses, 10 Hz, 180 mJ; n = 34) and cultured for 14 days. Bone lengths were measured on Days 0, 4, 7, and 14. After 14 days of culturing, growth plate morphology was assessed with a histomorphometric analysis in which hypertrophic cell size (> 7 µm) and hypertrophic zone height were measured (n = 6 bones each). Immunostaining for specific regulatory proteins involved in chondrogenesis and corresponding staining were quantitated digitally by a single observer using the automated threshold method in ImageJ software (n = 6 bones per group). A p value < 0.05 indicated a significant difference. RESULTS: The bone length in the high-dose rESWT group was increased compared with that in untreated controls (4.46 mm ± 0.75 mm; 95% confidence interval, 3.28-3.71 and control: 3.50 mm ± 0.38 mm; 95% CI, 4.19-4.72; p = 0.01). Mechanistic studies of the growth plate's cartilage revealed that high-dose rESWT increased the number of proliferative chondrocytes compared with untreated control bones (1363 ± 393 immunopositive cells per bone and 500 ± 413 immunopositive cells per bone, respectively; p = 0.04) and increased the diameter of hypertrophic chondrocytes (18 ± 3 µm and 13 ± 3 µm, respectively; p < 0.001). This was accompanied by activation of insulin-like growth factor-1 (1015 ± 322 immunopositive cells per bone and 270 ± 121 immunopositive cells per bone, respectively; p = 0.043) and nuclear factor-kappa beta signaling (1029 ± 262 immunopositive cells per bone and 350 ± 60 immunopositive cells per bone, respectively; p = 0.01) and increased levels of the anti-apoptotic proteins B-cell lymphoma 2 (718 ± 86 immunopositive cells per bone and 35 ± 11 immunopositive cells per bone, respectively; p < 0.001) and B-cell lymphoma-extra-large (107 ± 7 immunopositive cells per bone and 34 ± 6 immunopositive cells per bone, respectively; p < 0.001). CONCLUSION: In a model of cultured fetal rat metatarsals, rESWT increased longitudinal bone growth by locally inducing chondrogenesis. To verify whether rESWT can also stimulate bone growth in the presence of systemic circulatory factors, further studies are needed. CLINICAL RELEVANCE: This preclinical proof-of-concept study shows that high-dose rESWT can stimulate longitudinal bone growth and growth plate chondrogenesis in cultured fetal rat metatarsal bones. A confirmatory in vivo study in skeletally immature animals must be performed before any clinical studies.

Bidirectional relationship between eating disorders and autoimmune diseases.

BACKGROUND: Immune system dysfunction may be associated with eating disorders (ED) and could have implications for detection, risk assessment, and treatment of both autoimmune diseases and EDs. However, questions regarding the nature of the relationship between these two disease entities remain. We evaluated the strength of associations for the bidirectional relationships between EDs and autoimmune diseases. METHODS: In this nationwide population-based study, Swedish registers were linked to establish a cohort of more than 2.5 million individuals born in Sweden between January 1, 1979 and December 31, 2005 and followed up until December 2013. Cox proportional hazard regression models were used to investigate: (a) subsequent risk of EDs in individuals with autoimmune diseases; and (b) subsequent risk of autoimmune diseases in individuals with EDs. RESULTS: We observed a strong, bidirectional relationship between the two illness classes indicating that diagnosis in one illness class increased the risk of the other. In women, the diagnoses of autoimmune disease increased subsequent hazards of anorexia nervosa (AN), bulimia nervosa (BN), and other eating disorders (OED). Similarly, AN, BN, and OED increased subsequent hazards of autoimmune diseases.Gastrointestinal-related autoimmune diseases such as, celiac disease and Crohn's disease showed a bidirectional relationship with AN and OED. Psoriasis showed a bidirectional relationship with OED. The previous occurence of type 1 diabetes increased the risk for AN, BN, and OED. In men, we did not observe a bidirectional pattern, but prior autoimmune arthritis increased the risk for OED. CONCLUSIONS: The interactions between EDs and autoimmune diseases support the previously reported associations. The bidirectional risk pattern observed in women suggests either a shared mechanism or a third mediating variable contributing to the association of these illnesses.

High prevalence of pituitary hormone deficiency in both unilateral and bilateral optic nerve hypoplasia.

AIM: This study examined the prevalence of neurological impairment and pituitary hormone deficiency (PHD) in patients with unilateral and bilateral optic nerve hypoplasia (ONH). METHODS: A population-based cross-sectional cohort study of 65 patients (51% female) with ONH was conducted in Stockholm. Of these were 35 bilateral and 30 unilateral. The patients were below 20 years of age, living in Stockholm in December 2009 and found through database searching. The median age at the analysis of the results in January 2018 was 16.1 years (range 8.1-27.5 years). Neurological assessments and blood sampling were conducted, neuroradiology was reviewed and growth curves were analysed. Diagnoses of PHDs were based on clinical and biochemical evidence of hormone deficiency. RESULTS: Neurological impairments were identified in 47% of the patients and impairments in gross and fine motor function were more prevalent in bilateral ONH (p < 0.001). In addition, 9% had cerebral palsy and 14% had epilepsy. The prevalence of PHD was 29 and 19% had multiple PHD. CONCLUSION: Children with ONH had a high risk of neurological impairment, especially in bilateral disease. Both unilateral and bilateral ONH signified an increased prevalence of PHD and all these children should be endocrinologically followed up until completed puberty.

Identification of a clonally expanding haematopoietic compartment in bone marrow.

In mammals, postnatal haematopoiesis occurs in the bone marrow (BM) and involves specialized microenvironments controlling haematopoietic stem cell (HSC) behaviour and, in particular, stem cell dormancy and self-renewal. While these processes have been linked to a number of different stromal cell types and signalling pathways, it is currently unclear whether BM has a homogenous architecture devoid of structural and functional partitions. Here, we show with genetic labelling techniques, high-resolution imaging and functional experiments in mice that the periphery of the adult BM cavity harbours previously unrecognized compartments with distinct properties. These units, which we have termed hemospheres, were composed of endothelial, haematopoietic and mesenchymal cells, were enriched in CD150+ CD48- putative HSCs, and enabled rapid haematopoietic cell proliferation and clonal expansion. Inducible gene targeting of the receptor tyrosine kinase VEGFR2 in endothelial cells disrupted hemospheres and, concomitantly, reduced the number of CD150+ CD48- cells. Our results identify a previously unrecognized, vessel-associated BM compartment with a specific localization and properties distinct from the marrow cavity.

Somapacitan, a once-weekly reversible albumin-binding GH derivative, in children with GH deficiency: A randomized dose-escalation trial.

OBJECTIVE: To evaluate the safety, local tolerability, pharmacodynamics and pharmacokinetics of escalating single doses of once-weekly somapacitan, a reversible, albumin-binding GH derivative, vs once-daily GH in children with GH deficiency (GHD). DESIGN: Phase 1, randomized, open-label, active-controlled, dose-escalation trial (NCT01973244). PATIENTS: Thirty-two prepubertal GH-treated children with GHD were sequentially randomized 3:1 within each of four cohorts to a single dose of somapacitan (0.02, 0.04, 0.08 and 0.16 mg/kg; n=6 each), or once-daily Norditropin® SimpleXx® (0.03 mg/kg; n=2 each) for 7 days. MEASUREMENTS: Pharmacokinetic and pharmacodynamic profiles were assessed. RESULTS: Adverse events were all mild, and there were no apparent treatment-dependent patterns in type or frequency. Four mild transient injection site reactions were reported in three of 24 children treated with somapacitan. No antisomapacitan/anti-human growth hormone (hGH) antibodies were detected. Mean serum concentrations of somapacitan increased in a dose-dependent but nonlinear manner: maximum concentration ranged from 21.8 ng/mL (0.02 mg/kg dose) to 458.4 ng/mL (0.16 mg/kg dose). IGF-I and IGFBP-3, and change from baseline in IGF-I standard deviation score (SDS) and IGFBP-3 SDS, increased dose dependently; greatest changes in SDS values were seen for 0.16 mg/kg. IGF-I SDS values were between -2 and +2 SDS, except for peak IGF-I SDS with 0.08 mg/kg somapacitan. Postdosing, IGF-I SDS remained above baseline levels for at least 1 week. CONCLUSIONS: Single doses of once-weekly somapacitan (0.02-0.16 mg/kg) were well tolerated in children with GHD, with IGF-I profiles supporting a once-weekly treatment profile. No clinically significant safety/tolerability signals or immunogenicity concerns were identified.

Mutations in SLC34A3/NPT2c are associated with kidney stones and nephrocalcinosis.

Compound heterozygous and homozygous (comp/hom) mutations in solute carrier family 34, member 3 (SLC34A3), the gene encoding the sodium (Na(+))-dependent phosphate cotransporter 2c (NPT2c), cause hereditary hypophosphatemic rickets with hypercalciuria (HHRH), a disorder characterized by renal phosphate wasting resulting in hypophosphatemia, correspondingly elevated 1,25(OH)2 vitamin D levels, hypercalciuria, and rickets/osteomalacia. Similar, albeit less severe, biochemical changes are observed in heterozygous (het) carriers and indistinguishable from those changes encountered in idiopathic hypercalciuria (IH). Here, we report a review of clinical and laboratory records of 133 individuals from 27 kindreds, including 5 previously unreported HHRH kindreds and two cases with IH, in which known and novel SLC34A3 mutations (c.1357delTTC [p.F453del]; c.G1369A [p.G457S]; c.367delC) were identified. Individuals with mutations affecting both SLC34A3 alleles had a significantly increased risk of kidney stone formation or medullary nephrocalcinosis, namely 46% compared with 6% observed in healthy family members carrying only the wild-type SLC34A3 allele (P=0.005) or 5.64% in the general population (P<0.001). Renal calcifications were also more frequent in het carriers (16%; P=0.003 compared with the general population) and were more likely to occur in comp/hom and het individuals with decreased serum phosphate (odds ratio [OR], 0.75, 95% confidence interval [95% CI], 0.59 to 0.96; P=0.02), decreased tubular reabsorption of phosphate (OR, 0.41; 95% CI, 0.23 to 0.72; P=0.002), and increased serum 1,25(OH)2 vitamin D (OR, 1.22; 95% CI, 1.05 to 1.41; P=0.008). Additional studies are needed to determine whether these biochemical parameters are independent of genotype and can guide therapy to prevent nephrocalcinosis, nephrolithiasis, and potentially, CKD.

Expression of the aryl hydrocarbon receptor in growth plate cartilage and the impact of its local modulation on longitudinal bone growth.

Although dioxin has been reported to impair bone growth in both humans and animals, the underlying mechanisms have not been clarified. We conducted this study to rule out if dioxin may directly target the growth plate, via local modulation of the aryl hydrocarbon receptor (AhR). Initial studies in rare tissue samples of the human growth plate confirmed that the AhR protein is widely expressed in growth plate cartilage. To explore the local role of the AhR, mechanistic studies were performed in a well-established model of cultured fetal rat metatarsal bones. The longitudinal growth of these bones was monitored while being exposed to AhR modulators. The AhR agonist, 2,3,7,8-tetrachlorodibenzo-p-dioxin, did not affect bone growth at any concentrations tested (1 pM-10 nM). In contrast, the AhR antagonist, alpha-naphthoflavone, suppressed bone growth and increased chondrocyte apoptosis, although only at a high, potentially cytotoxic concentration (50 µM). We conclude that although the AhR is widely expressed in the growth plate, bone growth is not modulated when locally activated, and therefore, dioxin-induced growth failure is likely mediated through systemic rather than local actions.

Bortezomib treatment causes long-term testicular dysfunction in young male mice.

BACKGROUND: With increased long-term survivors of childhood cancer patients, therapy-associated infertility has become one of the most common late side-effects and significantly affects their life-quality. Therefore, evaluation of anti-cancer agents on male reproduction and infertility prevention are urgently demanding. The proteasome inhibitor bortezomib has been launched in clinical trials for childhood cancers, however, its potential side effects on reproduction have so far been neither investigated experimentally nor reported in treated children. Thus the present study is designed to explore the impact of bortezomib on male reproductive function and to gain insights into how bortezomib exerts its adverse effects on man gonad, thereby providing pediatric oncologists relevant information. METHODS: 35 day-old male mice were treated with one 11-day cycle of bortezomib and then sacrificed 2 days, 45 days, or 6 months later. A mating study was performed in the group followed for 6 months, and their pups were analyzed on postnatal day 50. Serum follicle-stimulating hormone (FSH) and testicular testosterone levels were measured. Testicular morphology was evaluated by light- and electron microscopy, and the underlying mechanisms and pathways of testis damage were investigated. RESULTS: Testicular damage was visible already 2 days after stopping bortezomib and increased in severity by day 45. Then 80% of seminiferous tubules exhibited hypospermatogenesis with arrest at the levels of spermatogonia, spermatocytes and round spermatids. Germ cells were specifically targeted by bortezomib as evidenced by increased apoptosis mediated through activation of p53 and caspases. Even six months after the bortezomib treatment, testis weight, sperm concentration and seminiferous tubule length remained at a decreased level, indicating that spermatogenesis and tubular outgrowth could not fully recover. Combined with persistently increased serum levels of FSH in these mice, our results demonstrate that bortezomib can have long-term effects on testicular function, although fertility of bortezomib-exposed males remained and their offspring looked healthy. CONCLUSION: Bortezomib treatment causes long-term gonadal dysfunction in male mice. Careful monitoring of gonadal function in male childhood cancer patients treated with bortezomib is thus strongly recommended.

Common DNA variants predict tall stature in Europeans.

Genomic prediction of the extreme forms of adult body height or stature is of practical relevance in several areas such as pediatric endocrinology and forensic investigations. Here, we examine 770 extremely tall cases and 9,591 normal height controls in a population-based Dutch European sample to evaluate the capability of known height-associated DNA variants in predicting tall stature. Among the 180 normal height-associated single nucleotide polymorphisms (SNPs) previously reported by the Genetic Investigation of ANthropocentric Traits (GIANT) genome-wide association study on normal stature, in our data 166 (92.2 %) showed directionally consistent effects and 75 (41.7 %) showed nominally significant association with tall stature, indicating that the 180 GIANT SNPs are informative for tall stature in our Dutch sample. A prediction analysis based on the weighted allele sums method demonstrated a substantially improved potential for predicting tall stature (AUC = 0.75; 95 % CI 0.72-0.79) compared to a previous attempt using 54 height-associated SNPs (AUC = 0.65). The achieved accuracy is approaching practical relevance such as in pediatrics and forensics. Furthermore, a reanalysis of all SNPs at the 180 GIANT loci in our data identified novel secondary association signals for extreme tall stature at TGFB2 (P = 1.8 × 10(-13)) and PCSK5 (P = 7.8 × 10(-11)) suggesting the existence of allelic heterogeneity and underlining the importance of fine analysis of already discovered loci. Extrapolating from our results suggests that the genomic prediction of at least the extreme forms of common complex traits in humans including common diseases are likely to be informative if large numbers of trait-associated common DNA variants are available.

Childhood growth hormone treatment: challenges, opportunities, and considerations.

With long standing demand and popularity, growth hormone treatments continue to be a topic of interest for paediatric endocrinologists and general paediatricians due to ongoing issues regarding their long-term effects, the safety of childhood treatment, and the introduction of long-acting growth hormone preparations in the past decade. Moreover, uncertainty regarding how to approach individual patients and their treatment indications remains, particularly concerning tailored treatment goals and objectives; this uncertainty is further complicated by the multitude of approved indications that surpass substitution therapy. The paediatric endocrinologist thus grapples with pertinent questions, such as what defines reasonable treatment goals for each individual given their indications, and when (and how) to initiate the necessary discussions about risks and benefits with patients and their families. The aim of this Review is to offer advanced physiological concepts of growth hormone function, map out approved paediatric indications for treatment along with evidence on their effects and safety, highlight controversies and complexities surrounding childhood growth hormone treatment, and discuss the potential of long-acting growth hormone and future directions in the realm of childhood growth hormone treatment.

Long-term risk of neoplastic events after childhood growth hormone treatment: a population-based cohort study in Sweden.

Background: Increased risk of neoplastic events after recombinant human growth hormone (rhGH) treatment in childhood has been an ongoing concern but long-term safety data are limited. Methods: A nationwide population-based cohort study in Sweden of patients treated with rhGH during childhood between 1985-2010, due to isolated growth hormone deficiency (GHD), small for gestational age (SGA) and idiopathic short stature (ISS). The comparison group consisted of 15 age-, sex-, and region-matched controls per patient, randomly selected from the general population. Data on neoplastic events and covariates, such as gestational age, birth weight, birth length, socioeconomic status, and height at study start, were collected through linkage with population-based registers. The cohort was followed for neoplastic events until the end of 2020. Results: 53,444 individuals (3,408 patients; 50,036 controls) were followed for up to 35 years, with a median follow-up of 19.8 years and a total of 1,050,977 person-years. Patients showed a moderately increased hazard ratio (HR) for neoplastic events overall compared to controls (HR 1.28, 95% CI: 1.12-1.46), but only significant for males (HR 1.39, 95% CI: 1.17-1.66) and not females (HR 1.15, 95% CI: 0.94-1.41). Longer treatment duration was associated with an increased HR, but no association was found between neoplastic events and mean or cumulative dose. No increased risk of malignant neoplasms was observed for the patients compared to matched controls (HR 0.91 95% CI: 0.66-1.26). Conclusion: No association was found between rhGH treatment during childhood for GHD, SGA, or ISS and malignant neoplastic events in early to mid-adulthood. A moderate increase in overall neoplastic events was observed due to an increased number of events in male patients.

Safety and Efficacy of Bilateral Epiphysiodesis Surgery to Reduce Final Height in Extremely Tall Adolescents - A Follow-up Study.

INTRODUCTION: Treatment options in patients with extreme tall stature are limited. Bilateral epiphysiodesis has emerged as a possible treatment method aiming to reduce final height. However, there is still insufficient data on long-term safety and final height outcome. Therefore, the aim of this study was to assess the efficacy and safety of bilateral epiphysiodesis to reduce final adult height in tall adolescents. METHODS: The study population consisted of 72 patients with extreme tall stature who were followed at the Pediatric Endocrine Clinic at the Karolinska University Hospital, Stockholm (Sweden) and subsequently underwent bilateral epiphysiodesis around the knees (girls n=45, boys n=27). RESULTS: When compared to the final height prediction at time of surgery, the procedure significantly reduced the achieved final height by a mean of 3.6 cm ± 0.4 cm in girls (p<0.001; 26.0 ± 2.9 % reduction) and 8.6 ± 0.9 cm in boys (p<0.001; 40.5 ± 3.0 % reduction). Furthermore, a negative correlation was observed between the absolute height reduction and the bone age at time of surgery, which was stronger in boys (r=-0.63, p<0.001) than in girls (r=-0.44, p<0.001). Besides reducing final height, body proportions were affected in all patients subjected to bilateral epihyseodesis. However, as tall individuals typically have relatively long legs, body proportions were rather normalized after the surgery. There were no serious complications reported. CONCLUSION: This study suggests that bilateral epiphysiodesis is an efficient and safe method to reduce final height in extremely tall adolescent girls and boys. The achieved height reduction was higher in boys and when performed at an earlier bone age. Importantly, no serious side-effects were reported. However, a continued follow-up is still warranted to detect any potential rare complications.

Humanin Treatment Protects Against Venetoclax-Induced Bone Growth Retardation in Ex Vivo Cultured Rat Bones.

Context: Recent preclinical studies reported that the BCL-2 inhibitor venetoclax can impair bone growth. A strategy to prevent such a side effect of this promising anticancer drug is highly desired. Earlier in vitro and in vivo studies suggested that the mitochondrial peptide humanin has the potential to prevent drug-induced growth impairment. Objective: We hypothesized that co-treatment with the humanin analog HNG may prevent venetoclax-induced bone growth impairment. Methods: Ex vivo studies were performed in fetal rat metatarsal bones and human growth plate samples cultured for 12 and 2 days, respectively, while in vivo studies were performed in young neuroblastoma mice being treated daily for 14 days. The treatment groups included venetoclax, HNG, venetoclax plus HNG, or vehicle. Bone growth was continuously monitored and at the end point, histomorphometric and immunohistochemical analyses were performed in fixed tissues. Results: Venetoclax suppressed metatarsal bone growth and when combined with HNG, bone growth was rescued and all histological parameters affected by venetoclax monotherapy were normalized. Mechanistic studies showed that HNG downregulated the pro-apoptotic proteins Bax and p53 in cultured metatarsals and human growth plate tissues, respectively. The study in a neuroblastoma mouse model confirmed a growth-suppressive effect of venetoclax treatment. In this short-term in vivo study, no significant bone growth-rescuing effect could be verified when testing HNG at a single dose. We conclude that humanin dose-dependently protects ex vivo cultured metatarsal bones from venetoclax-induced bone growth impairment by restoring the growth plate microstructure.

The automated Greulich and Pyle: a coming-of-age for segmental methods?

The well-known Greulich and Pyle (GP) method of bone age assessment (BAA) relies on comparing a hand X-ray against templates of discrete maturity classes collected in an atlas. Automated methods have recently shown great success with BAA, especially using deep learning. In this perspective, we first review the success and limitations of various automated BAA methods. We then offer a novel hypothesis: When networks predict bone age that is not aligned with a GP reference class, it is not simply statistical error (although there is that as well); they are picking up nuances in the hand X-ray that lie "outside that class." In other words, trained networks predict distributions around classes. This raises a natural question: How can we further understand the reasons for a prediction to deviate from the nominal class age? We claim that segmental aging, that is, ratings based on characteristic bone groups can be used to qualify predictions. This so-called segmental GP method has excellent properties: It can not only help identify differential maturity in the hand but also provide a systematic way to extend the use of the current GP atlas to various other populations.