A simple rodent subcutaneous assay for identification of new osteoinductive molecules: The key method for screening of novel bone regeneration implants

Treatment of large bone defects and degenerative diseases of the spine is among the most challeng- ing and still unresolved issues in clinical medicine. Therefore, substantial effort has been devoted to the development of novel bone regenerative therapies. Due to their potent osteoinductive properties, Bone Morphogenetic Proteins (BMPs) have been the basis for the development of novel strategies for bone regeneration. The use of animal models is an indispensable part of the preclinical testing of novel therapeutic solutions. The rat subcutaneous assay became the initial screening procedure for the evalu- ation of promising BMP-based osteoinductive devices for bone regeneration because only osteogenic BMPs can induce new bone at any ectopic rodent site. Moreover, this model is used for research on the mechanisms of ectopic bone formation as well as for the evaluation of the inflammatory response to different materials. In this review, we provided an overview of the assay development and previously conducted studies with different methods (flow cytometry, histological and microCT analyses) for the study outcome evaluation. Moreover, we addressed essential issues in the experimental design such as the follow-up period and the sample size. The rat subcutaneous bone induction assay layed the founda- tion for isolation and identification of BMPs followed by testing of new osteogenic devices in higher animal species and humans

Osteogenic Protein-1 Is Produced by Human Fetal Trophoblasts In Vivo and Regulates the Synthesis of Chorionic Gonadotropin and Progesterone by Trophoblasts In Vitro

Peer Reviewe

State-of-the-art of the Bone Morphogenetic Protein research field: 13th International BMP Conference, Dubrovnik 2022

The 13th International BMP Conference was held in October 2022 in Dubrovnik. The conference was attended by more than 240 participants from North America, Europe, Asia, and Australia who got an insight into the latest achievements in basic, translational, and clinical research of BMP mol- ecules through 75 lectures categorized into several scientific sections. This review paper provides the most important novel findings on the structure, function, and signaling of BMPs, the role of BMPs in patterning and organoids as well as the role of BMP in metabolism. Moreover, we discussed the role of BMPs in various diseases including cancer pathogenesis, pulmonary arterial hyperten- sion, and fibrodysplasia ossificans progressiva (FOP). Finally, we provided an overview of the new BMP-based therapies in regenerative medicine that are currently in different stages of preclinical and clinical trials

Autologous blood coagulum containing rhBMP6 induces new bone formation to promote anterior lumbar interbody fusion (ALIF) and posterolateral lumbar fusion (PLF) of spine in sheep

resent study, we evaluated an autologous bone graft substitute (ABGS) composed of recombinant human BMP6 (rhBMP6) dispersed within autologous blood coagulum (ABC) used as a physiological carrier for new bone formation in spine fusion sheep models. The application of ABGS included cervical cage for use in the anterior lumbar interbody fusion (ALIF), while for the posterolateral lumbar fusion (PLF) sheep model allograft devitalized bone particles (ALLO) were applied with and without use of instrumentation. In the ALIF model, ABGS (rhBMP6/ABC/cage) implants fused significantly when placed in between the denuded L4- L5 vertebrae as compared to control (ABC/cage) which appears to have a fibrocartilaginous gap, as examined by histology and micro CT analysis at 16 weeks following surgery. In the PLF model, ABGS implants with or without ALLO showed a complete fusion when placed ectopically in the gutter bilaterally between two decorticated L4-L5 transverse processes at a success rate of 88% without instrumentation and at 80% with instrumentation ; however the bone volume was 50% lower in the instrumentation group than without, as examined by histology, radiographs, micro CT analyses and biomechanical testing at 27 weeks following surgery. The newly formed bone was uniform within ABGS implants resulting in a biomechanically competent and histologically qualified fusion with an optimum dose in the range of 100 g rhBMP6 per mL ABC, while in the implants that contained ALLO, the mineralized bone particles were substituted by the newly formed remodeling bone via creeping substitution. These findings demonstrate for the first time that ABGS (rhBMP6/ABC) without and with ALLO particles induced a robust bone formation with a successful fusion in sheep models of ALIF and PLF, and that autologous blood coagulum (ABC) serves as a preferred physiological native carrier to induce new bone at low doses of rhBMP6 and to achieve a successful spinal fusion

Koštani morfogenetski proteini (BMP): Od otkrića do razvoja nove autologne koštane naprave koja se sastoji od rekombinantnog humanog BMP6 u autolognom krvnom ugrušku kao nosaču

Bone Morphogenetic Proteins (BMPs) are growth and differentiation factors within the TGFβ superfam- ily of proteins. They induce ectopic and orthotopic endochondral bone formation and are involved in the regulation of cell proliferation, differentiation, apoptosis and mesenchymal-epithelial interactions in critical morphogenetic processes of tissues beyond bone. BMP2 and BMP7 osteogenic devices have been approved for enhancing healing in patients with long bone defects and anterior spinal fusion proce- dures. However, due to a high price and various serious adverse events including heterotopic ossifica- tion, retrograde ejaculation and pain their clinical use have been limited. In this review we discuss the BMP discovery, biology and their use in clinical studies with particular reference to the newly developed BMP6 based autologous bone graft substitute (ABGS). A novel ABGS consisting of an autologous bone coagulum (ABC) carrier with dispersed BMP6 to initiate the differentiation of mesenchymal cells into endochondral bone. The ABC met the conditions for an optimal delivery system for BMP6 due to han- dling simplicity, without an immunogenic and inflammatory response at the implantation site. Addition of allograft or synthetic ceramics to ABGS demonstrated in animal models significantly increased volume and better microarchitecture of the newly formed bone. The first clinical study was conducted in patients with distal radial fractures (Phase I study) and the second in patients undergoing high tibial osteotomy (Phase I/II study) and no serious adverse events have been observed. Finally, in the ongoing OSTEO- proSPINE study ABGS enforced with allograft bone is evaluated in patients with chronic back pain due to degenerative disc diseases. The novel ABGS bone mimetic is a major breakthrough and contribution to bone biology and regenerative medicine of skeletal repair.Koštani morfogenetski proteini (BMP) čine grupu čimbenika rasta i diferencijacije unutar TGFβ nado- bitelji. Oni induciraju stvaranje ektopične i ortotopične endohondralne kosti te su uključeni u regulaciju stanične proliferacije, diferencijacije, apoptoze i mezenhimalno-epitelne interakcije u važnim tkivnim morfogenetskim procesima izvan koštanog sustava. Koštane naprave koje sadrže BMP2 i BMP7 pro- tein odobrene su za poboljšanje koštanog cijeljenja kod pacijenata s defektima dugih cjevastih kostiju i kod prednje spinalne fuzije kralježnice. Međutim, zbog visoke cijene i mnogobrojnih nuspojava koje su uključivale pojavu heterotopičnih osifikacija, retrogradnu ejakulaciju i bol, njihova je klinička prim- jena ograničena. U ovom smo preglednom radu raspravili otkriće BMP molekula, njihovu biologiju i primjenu u kliničkim studijama s posebnim osvrtom na nedavno otkrivenu novu autolognu koštanu napravu (ABGS) koja sadrži BMP6. Novi ABGS sastoji se od nosača autolognog koaguluma (ABC) s otopljenim BMP6 koji je ključan za pokretanje diferencijacije mezenhimalnih stanica u smjeru stvaranja endohondralne kosti. ABC je ispunio sve potrebne uvjete za formulaciju optimalnog nosača za BMP6 isključivo zbog jednostavnosti priprave i primjene te odsustva imunogenog i upalnog odgovora na mjestu implantacije. Uz dodatak alografta ili sintetičke keramike što je potvrđeno na životinjskim modelima došlo je do značajnog povećanja volumena te poboljšanja mikroarhitekture novonastale kosti. Prvo kliničko ispitivanje provedeno je na pacijentima s distalnim prijelomima radijusa (faza I studije), a drugo na pacijentima koji su podvrgnuti visokoj osteotomiji tibije (faza I/II studije) bez uočenih ozbiljnih nuspojava. Trenutno je u tijeku studija OSTEOproSPINE u kojoj se testira učinkovitost ABGS u kom- binaciji s koštanim alograftom u bolesnika s kroničnim bolovima u leđima uzrokovanim degenerativnim promjenama intervertebralnog diska. Nova ABGS koštana naprava značajna je prekretnica i napredak u području koštane biologije te regenerativne medicine koštanog sustava

Biology of bone morphogenetic protein in bone repair and regeneration: A role for autologous blood coagulum as carrier

BMPs were purified from demineralized bone matrix based on their ability to induce new bone in vivo and they represent a large member of the TGF-β superfamily of proteins. BMPs serve as morphogenic signals for mesenchymal stem cell migration, proliferation and subsequently differentiation into cartilage and bone during embryonic development. A BMP when implanted with a collagenous carrier in a rat subcutaneous site is capable of inducing new bone by mimicking the cellular events of embryonic bone formation. Based on this biological principle, BMP2 and BMP7 containing collagenous matrix as carrier have been developed as bone graft substitutes for spine fusion and long bone fractures. Here, we describe a novel autologous bone graft substitute that contains BMP6 delivered within an autologous blood coagulum as carrier and summarize the biology of osteogenic BMPs in the context of bone repair and regeneration specifically the critical role that carrier plays to support osteogenesis

Morphogenesis of Digits in the Avian Limb Is Controlled by FGFs, TGFβs, and Noggin through BMP Signaling

AbstractIn the final stages of limb morphogenesis, autopodial cells leaving the progress zone differentiate into cartilage or undergo apoptotic cell death, depending on whether they are incorporated into the digital rays or interdigital spaces. Most evidence indicates that these two opposite fates of the autopodial mesoderm are controlled by BMP signaling. However, the molecular basis for these two distinct actions of BMPs, including the receptors involved in the process, is controversial. In this study we have addressed this question by exploring the presence in the developing autopod of diffusible signals able to modulate BMP function and by analyzing the effects of their exogenous administration on the pattern of expression of BMP receptor genes. Our findings show thattgfβ2andnoggingenes are expressed in the condensing region of the developing digital rays in addition to the well-known distribution in the autopodial tissues of FGFs (apical ectodermal ridge, AER) and BMPs (AER, progress zone mesoderm, and interdigital regions). Exogenous administration of all the factors causes changes in the expression of thebmpR-1bgene which are followed by parallel alterations of the skeletal phenotype: FGFs inhibit the expression ofbmpR-1bcompatible with their function in the maintenance of the progress zone mesoderm in an undifferentiated state; and TGFβs induce the expression ofbmpR-1band promote ectopic chondrogenesis, compatible with a function in the establishment of the position of the digital rays. In addition we provide evidence for the occurrence of an interactive loop between BMPs and noggin accounting for the spatial distribution ofbmpR-1bwhich may control the size and shape of the skeletal pieces. In contrast to thebmpR-1bgene, thebmpR-1agene is expressed at low levels in the autopodial mesoderm and its expression is not modified by any of the tested factors regardless of their effects on chondrogenesis or cell death. Finally, the role of BMPs in programmed cell death is confirmed here by the intense inhibitory effect of noggin on apoptosis, but the lack of correlation between changes in the pattern of cell death induced by treatment with the studied factors and the expression of eitherbmpR-1aorbmpR-1bgenes suggest that a still-unidentified BMP receptor may account for this BMP function