Congenital disorders of bone and blood

Rare Cause of Bone Marrow Failure: Osteopetrosis, Case Series

Osteopetrosis is a rare metabolic bone disease that can lead to progressive bone marrow failure if left untreated. Resulting cytopenia and extramedullary hematopoiesis are frequently encountered in autosomal recessive form of the disease (ARO) and may result in death. Recurrent bone fractures and skeletal deformities are mostly seen in autosomal dominant form osteopetrosis (ADO) and cause significant morbidity. In this report, clinical, laboratory, and radiological findings of 5 patients with osteopetrosis were presented. Three had cytopenias, typical peripheral smear, and bone marrow aspiration findings regarding bone marrow failure as well as extensively increased bone density which was a classical radiological appearance. Two of them had TCIRG1 mutations associated with ARO, died because of severe infections. One with certain findings of ARO without genetic analysis is alive after hematopoietic stem cell transplantation. Two siblings had novel variants of CLCN7 (NM_001114331) p.Val755Serfs*4 (c.2263del) heterozygocity, associated with ADO and severe skeletal problems. One had been followed up also for nephrotic syndrome. Detection of genetic abnormalities is important as well as typical physical examination findings and, presence of hematological or radiological indicators in definitive diagnosis of the disease. Although osteopetrosis is rare, it is a potentially fatal disease that should be considered in the differential diagnosis.

Alendronate preserves bone mineral density in adults with sickle cell disease and osteoporosis

Low bone mineral density is highly prevalent in sickle cell disease (SCD); whether bisphosphonates can safely preserve or increase bone mass in SCD adults remains unknown. In this study, lumbar spine bone density remained stable with alendronate use, and treatment-related side effects were mostly mild and self-limited.

PURPOSE

To describe the effects of alendronate in adults with sickle cell disease (SCD) and osteoporosis.

METHODS

We reviewed retrospective clinical data from adults with SCD and osteoporosis treated with alendronate at a single center in Brazil (2009-2019). Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) of the lumbar spine, femoral neck, and total hip. We analyzed BMD changes by alendronate treatment duration (months), stratified by sex, skeletal site, and SCD genotype.

RESULTS

Sixty-four SCD adults with osteoporosis (69% females, 73% HbSS, mean age ± standard deviation 42.4 ± 10.9 years) received alendronate for a median (interquartile range) of 48 (29, 73) months. Compared with males, females had significantly lower baseline BMD (g/cm2) at the femoral neck (0.72 vs 0.85, p =  < 0.001) and total hip (0.79 vs 0.88, p = 0.009). The between-sex differences in BMD changes were insignificant. Mean lumbar spine BMD significantly changed by 0.0357 g/cm2 (p = 0.028) in those on alendronate for > 5 years. Four adults (6.3%) reported mild therapy-related side effects. An atypical femoral diaphysis fracture, attributed to alendronate, was incidentally noted in a 37-year-old man on treatment for 4 years.

CONCLUSION

In this retrospective cohort of adults with SCD and osteoporosis on alendronate for a median of 48 months, we found no significant interactions between sex and changes in lumbar spine, femoral neck, or total hip BMD with alendronate. Lumbar spine BMD was stable in those on alendronate for < 5 years. Side effects of alendronate were mild, though one patient developed an atypical femoral fracture.

Correction of osteopetrosis in the neonate oc/oc murine model after lentiviral vector gene therapy and non-genotoxic conditioning

Introduction

Autosomal recessive osteopetrosis (ARO) is a rare genetic disease, characterized by increased bone density due to defective osteoclast function. Most of the cases are due to TCIRG1 gene mutation, leading to severe bone phenotype and death in the first years of life. The standard therapy is the hematopoietic stem cell transplantation (HSCT), but its success is limited by several constraints. Conversely, gene therapy (GT) could minimize the immune-mediated complications of allogeneic HSCT and offer a prompt treatment to these patients.

Methods

The Tcirg1-defective oc/oc mouse model displays a short lifespan and high bone density, closely mirroring the human condition. In this work, we exploited the oc/oc neonate mice to optimize the critical steps for a successful therapy.

Results

First, we showed that lentiviral vector GT can revert the osteopetrotic bone phenotype, allowing long-term survival and reducing extramedullary haematopoiesis. Then, we demonstrated that plerixafor-induced mobilization can further increase the high number of HSPCs circulating in peripheral blood, facilitating the collection of adequate numbers of cells for therapeutic purposes. Finally, pre-transplant non-genotoxic conditioning allowed the stable engraftment of HSPCs, albeit at lower level than conventional total body irradiation, and led to long-term survival and correction of bone phenotype, in the absence of acute toxicity.

Conclusion

These results will pave the way to the implementation of an effective GT protocol, reducing the transplant-related complication risks in the very young and severely affected ARO patients.

Inhibition of FGF23 is a therapeutic strategy to target hematopoietic stem cell niche defects in β-thalassemia

Clinical evidence highlights a relationship between the blood and the bone, but the underlying mechanism linking these two tissues is not fully elucidated. Here, we used β-thalassemia as a model of congenital anemia with bone and bone marrow (BM) niche defects. We demonstrate that fibroblast growth factor 23 (FGF23) is increased in patients and mice with β-thalassemia because erythropoietin induces FGF23 overproduction in bone and BM erythroid cells via ERK1/2 and STAT5 pathways. We show that in vivo inhibition of FGF23 signaling by carboxyl-terminal FGF23 peptide is a safe and efficacious therapeutic strategy to rescue bone mineralization and deposition in mice with β-thalassemia, normalizing the expression of niche factors and restoring hematopoietic stem cell (HSC) function. FGF23 may thus represent a molecular link connecting anemia, bone, and the HSC niche. This study provides a translational approach to targeting bone defects and rescuing HSC niche interactions, with potential clinical relevance for improving HSC transplantation and gene therapy for hematopoietic disorders.

Osseointegration of Dental Implants in Patients with Congenital and Degenerative Bone Disorders: A Literature Review

Aims and Objectives

The aim of this study was to describe the mechanism of dental implants osseointegration in patients with congenital and degenerative genetic bone disorders.

Materials and Methods

A PubMed and Scopus documents search was carried out between November 2021 in the, using words such as "osseointegration," "degenerative disease," "congenital disease," and "dental implants."

Results

The thirteen articles selected dealt with dental implants osseointegration in patients with congenital and degenerative bone disorders. The influence and repercussion of these diseases on the bone system, as well as the osseointegration process were described from healing to bone remodeling. In addition, certain articles described some considerations to improve the osseointegration process in patients suffering from these types of conditions.

Conclusions

Within the limitations of this literature review we can conclude that osseointegration in patients with ectodermal dysplasia and osteoporosis could be achieved. However, the planning process for dental implant placement in these patients should be more meticulous and individualized considering the degree of tissue involvement as well as the patient's age and skeletal development compared to systemically healthy patients.

A cross-sectional nationwide survey of osteosclerotic skeletal dysplasias in Japan

BACKGROUND

The osteosclerotic skeletal dysplasias (OSSDs) are a heterogeneous group of disorders characterized by systemic bone sclerosis. Little is known about OSSDs because of their rarity. We conducted a cross-sectional nationwide survey of OSSDs and examined the incidence, epidemiology, and therapeutic interventions on these disorders.

METHODS

This study consisted of a two-step survey. The number of patients with OSSDs who had visited medical institutions between April 2017 and March 2018 was reported from a total of 341 facilities (1364 departments from pediatrics, orthopaedic surgery, neurosurgery, and otolaryngology in each facility) by the first questionnaire. In the secondary survey, their clinical features were assessed by collecting demographic data, diagnostic details, current status, family histories, therapeutic interventions, histories of bone fracture and osteomyelitis, severity assessed by the modified Rankin Scale (mRS) and recent lifestyle conditions of the patient by the EQ-5D.

RESULTS

In the first survey, 51 facilities (56 departments) reported one or more OSSDs patients, including 50 patients with osteopetrosis and 57 patients of other OSSDs. Among 87 patients eligible for inclusion in the analysis in the secondary survey, we investigated detailed information on the 42 patients with osteopetrosis. The number of initial visits of osteopetrosis patients during the surveillance period was five per year, indicating that the estimated incidence of osteopetrosis seemed to be 0.6 per 100,000 live births. Eighty-six bone fractures were reported in 22 patients (52%), and interventions of pseudarthrosis were conducted in five patients. Nine patients (23%) showed significant disabilities with the mRS of grade 3 or higher. Neurological complications and severe anemia were the factors that deteriorate patients' quality of life.

CONCLUSIONS

This is the first study to examine the detailed epidemiology of OSSDs in Japan. We demonstrated that the incidence of OSSDs is extremely rare. Bone fragility and delayed fracture healing seem to be important orthopaedic problems for patients with osteopetrosis.

Anemia in the pediatric patient

The World Health Organization estimates that approximately a quarter of the world's population suffers from anemia, including almost half of preschool-age children. Globally, iron deficiency anemia is the most common cause of anemia. Other important causes of anemia in children are hemoglobinopathies, infection, and other chronic diseases. Anemia is associated with increased morbidity, including neurologic complications, increased risk of low birth weight, infection, and heart failure, as well as increased mortality. When approaching a child with anemia, detailed historical information, particularly diet, environmental exposures, and family history, often yield important clues to the diagnosis. Dysmorphic features on physical examination may indicate syndromic causes of anemia. Diagnostic testing involves a stepwise approach utilizing various laboratory techniques. The increasing availability of genetic testing is providing new mechanistic insights into inherited anemias and allowing diagnosis in many previously undiagnosed cases. Population-based approaches are being taken to address nutritional anemias. Novel pharmacologic agents and advances in gene therapy-based therapeutics have the potential to ameliorate anemia-associated disease and provide treatment strategies even in the most difficult and complex cases.

High platelet count is associated with low bone mineral density: The MrOS Sweden cohort

In elderly ambulatory men, high platelet and high neutrophil counts are related to low bone mineral density (BMD), after adjustment for relevant covariates. Low hemoglobin (hgb) is even associated with low BMD, but this relationship seems to be dependent on estradiol and osteocalcin.

PURPOSE

Blood and bone cells exist in close proximity to each other in the bone marrow. Accumulating evidence, from both preclinical and clinical studies, indicates that these cell types are interconnected. Our hypothesis was that BMD measurements are associated with blood count variables and bone remodeling markers.

METHODS

We analyzed blood count variables, bone remodeling markers, and BMD, in subjects from the MrOS cohort from Gothenburg, Sweden. Men with at least one blood count variable (hgb, white blood cell count, or platelet count) analyzed were included in the current analysis (n = 1005), median age 75.3 years (range 69-81 years).

RESULTS

Our results show that high platelet counts were related to low BMD at all sites (total hip BMD; r = - 0.11, P = 0.003). No statistically significant association was seen between platelet counts and bone remodeling markers. Neutrophil counts were negatively associated with total body BMD (r = - 0.09, P = 0.006) and total hip BMD (r = - 0.08, P = 0.010), and positively related to serum ALP (r = 0.15, P < 0.001). Hgb was positively related to total hip BMD (r = 0.16, P < 0.001), and negatively to serum osteocalcin (r = - 0.13, P < 0.001). The association between platelet and neutrophil counts and total hip BMD was statistically significant after adjustments for other covariates, but the association between hgb and total hip BMD was dependent on estradiol and osteocalcin.

CONCLUSIONS

Our observations support the hypothesis of an interplay between blood and bone components.

Bone fragility in patients affected by congenital diseases non skeletal in origin

BACKGROUND

Bone tissue represents a large systemic compartment of the human body, with an active metabolism, that controls mineral deposition and removal, and where several factors may play a role. For these reasons, several non-skeletal diseases may influence bone metabolism. It is of a crucial importance to classify these disorders in order to facilitate diagnosis and clinical management. This article reports a taxonomic classification of non-skeletal rare congenital disorders, which have an impact on bone metabolism METHODS: The International Osteoporosis Foundation (IOF) Skeletal Rare Diseases Working Group (SRD-WG), comprised of basic and clinical scientists, has decided to review the taxonomy of non-skeletal rare disorders that may alter bone physiology.

RESULTS

The taxonomy of non-skeletal rare congenital disorders which impact bone comprises a total of 6 groups of disorders that may influence the activity of bone cells or the characteristics of bone matrix.

CONCLUSIONS

This paper provides the first comprehensive taxonomy of non-skeletal rare congenital disorders with impact on bone physiology.

Expanded circulating hematopoietic stem/progenitor cells as novel cell source for the treatment of TCIRG1 osteopetrosis

Allogeneic hematopoietic stem cell transplantation is the treatment of choice for autosomal recessive osteopetrosis caused by defects in the TCIRG1 gene. Despite recent progress in conditioning, a relevant number of patients are not eligible for allogeneic stem cell transplantation because of the severity of the disease and significant transplant-related morbidity. We exploited peripheral CD34+ cells, known to circulate at high frequency in the peripheral blood of TCIRG1-deficient patients, as a novel cell source for autologous transplantation of gene corrected cells. Detailed phenotypical analysis showed that circulating CD34+ cells have a cellular composition that resembles bone marrow, supporting their use in gene therapy protocols. Transcriptomic profile revealed enrichment in genes expressed by hematopoietic stem and progenitor cells (HSPCs). To overcome the limit of bone marrow harvest/ HSPC mobilization and serial blood drawings in TCIRG1 patients, we applied UM171-based ex-vivo expansion of HSPCs coupled with lentiviral gene transfer. Circulating CD34+ cells from TCIRG1-defective patients were transduced with a clinically-optimized lentiviral vector (LV) expressing TCIRG1 under the control of phosphoglycerate promoter and expanded ex vivo. Expanded cells maintained long-term engraftment capacity and multi-lineage repopulating potential when transplanted in vivo both in primary and secondary NSG recipients. Moreover, when CD34+ cells were differentiated in vitro, genetically corrected osteoclasts resorbed the bone efficiently. Overall, we provide evidence that expansion of circulating HSPCs coupled to gene therapy can overcome the limit of stem cell harvest in osteopetrotic patients, thus opening the way to future gene-based treatment of skeletal diseases caused by bone marrow fibrosis.

Preparation and in vitro evaluation of PLA/biphasic calcium phosphate filaments used for fused deposition modelling of scaffolds

Ceramic materials such as calcium phosphates (CaPs) with a composition similar to the mineral phase of bones and polymeric polylactic acid (PLA) are potential candidates for the manufacturing of scaffolds to act as bone substitutes and for tissue engineering applications, due to their bioresorbability and biocompatibility. Variables such as porosity, topography, morphology, and mechanical properties play an essential role in the scaffolds response. In this paper, a polymer/ceramic composite filament of 1.7 mm in diameter based on PLA and biphasic calcium phosphates (BCPs) was obtained by hot-melt extrusion in a single screw extruder. The particles of BCP were obtained by solution-combustion synthesis, and the PLA used was commercial grade. The BCPs ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM), transmission electron microscopy (TEM), and Brunauer, Emmett, and Teller (BET). It was possible to confirm that the main inorganic phases were hydroxyapatite (HAP) and tricalcium phosphate (TCP) with grain sizes below 100 nm and with high porosity. The Filaments obtained are a bit fragile but were able to be used in fused deposition modelling (FDM) using low-cost commercial printers. The filaments were characterized by SEM and energy dispersive X-ray (EDX). The in-vitro tests of filaments showed deposition of apatite phases on their surface, non-cytotoxic behavior, adequate cell proliferation and cell adhesion.