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"Steinbacher, Derek"
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Aesthetic Orthognathic Surgery and Rhinoplasty
Comprehensive in scope, Aesthetic Orthognathic Surgery and Rhinoplasty presents orthognathic surgery from an aesthetic perspective, encompassing analysis, diagnosis, treatment, 3D virtual planning, and adjunctive procedures.
* Easily accessible clinical information presented in a concise and approachable format
* Well-illustrated throughout with more than1, 000 clinical photographs
* Includes access to a companion website with videos of surgical procedures
De novo mutations in inhibitors of Wnt, BMP, and Ras/ERK signaling pathways in non-syndromic midline craniosynostosis
2017
Non-syndromic craniosynostosis (NSC) is a frequent congenital malformation in which one or more cranial sutures fuse prematurely. Mutations causing rare syndromic craniosynostoses in humans and engineered mouse models commonly increase signaling of the Wnt, bone morphogenetic protein (BMP), or Ras/ERK pathways, converging on shared nuclear targets that promote bone formation. In contrast, the genetics of NSC is largely unexplored. More than 95% of NSC is sporadic, suggesting a role for de novo mutations. Exome sequencing of 291 parent–offspring trios with midline NSC revealed 15 probands with heterozygous damaging de novo mutations in 12 negative regulators of Wnt, BMP, and Ras/ERK signaling (10.9-fold enrichment, P = 2.4 × 10−11). SMAD6 had 4 de novo and 14 transmitted mutations; no other gene had more than 1. Four familial NSC kindreds had mutations in genes previously implicated in syndromic disease. Collectively, these mutations contribute to 10% of probands. Mutations are predominantly loss-of-function, implicating haploinsufficiency as a frequent mechanism. A common risk variant near BMP2 increased the penetrance of SMAD6 mutations and was overtransmitted to patients with de novo mutations in other genes in these pathways, supporting a frequent two-locus pathogenesis. These findings implicate new genes in NSC and demonstrate related pathophysiology of common non-syndromic and rare syndromic craniosynostoses. These findings have implications for diagnosis, risk of recurrence, and risk of adverse neurodevelopmental outcomes. Finally, the use of pathways identified in rare syndromic disease to find genes accounting for non-syndromic cases may prove broadly relevant to understanding other congenital disorders featuring high locus heterogeneity.
Journal Article
Two locus inheritance of non-syndromic midline craniosynostosis via rare SMAD6 and common BMP2 alleles
by
Choi, Jungmin
,
Hashim, Peter W
,
Mane, Shrikant
in
Alleles
,
Bone Morphogenetic Protein 2 - genetics
,
Cranial sutures
2016
Premature fusion of the cranial sutures (craniosynostosis), affecting 1 in 2000 newborns, is treated surgically in infancy to prevent adverse neurologic outcomes. To identify mutations contributing to common non-syndromic midline (sagittal and metopic) craniosynostosis, we performed exome sequencing of 132 parent-offspring trios and 59 additional probands. Thirteen probands (7%) had damaging de novo or rare transmitted mutations in SMAD6, an inhibitor of BMP – induced osteoblast differentiation (p<10−20). SMAD6 mutations nonetheless showed striking incomplete penetrance (<60%). Genotypes of a common variant near BMP2 that is strongly associated with midline craniosynostosis explained nearly all the phenotypic variation in these kindreds, with highly significant evidence of genetic interaction between these loci via both association and analysis of linkage. This epistatic interaction of rare and common variants defines the most frequent cause of midline craniosynostosis and has implications for the genetic basis of other diseases. The bones in the front, back and sides of the human skull are not fused to one another at birth in order to allow the brain to double in size during the first year of life and continue growing into adulthood. However, one in 2,000 infants is born with a condition called craniosynostosis in which some of these bones have already fused. This fusion prevents the skull from growing properly, and can lead to the brain becoming compressed. As such, surgeons routinely undo the fusion in these infants to allow the brain and skull to grow normally. Eighty-five percent of craniosynostosis cases occur in infants with no other abnormalities, (called non-syndromic cases) and most have no other affected family member. It has therefore been unclear whether these infants have craniosynostosis due to a genetic or non-genetic cause. If the cause is genetic, it is also not clear whether a mutation in a single gene, the combined effects of many genes, or something in between is responsible. Now, by focusing on a group of 191 infants with premature fusion of bones joined at the midline of the skull, Timberlake et al. asked if any of the approximately 20,000 genes in the human genome were altered more frequently in these infants than would be expected by chance. This search revealed that rare mutations that disable one copy of a gene called SMAD6 in combination with a common DNA variant near another gene called BMP2 account for about 7% of infants with midline forms of craniosynostosis. These genes are both known to regulate how bones form, which explains how the mutation of these genes could lead to craniosynostosis. In all cases, the parents of these children were unaffected. This was typically because one parent had only the SMAD6 mutation while the other had only the common BMP2 variant; the transmission of both to their offspring resulted in craniosynostosis. The finding that a rare mutation’s effect is strongly modified by a common variant from another site in the genome is unprecedented. These findings will allow doctors to counsel families about the risk of having additional children with craniosynostosis. Timberlake et al. next plan to study more patients with craniosynostosis to identify additional genes that contribute to this disease. They will also look at other diseases to see whether the combination of rare mutation and common DNA variant could be behind other unexplained disorders.
Journal Article
Vascularization of Natural and Synthetic Bone Scaffolds
by
Qian, Hong
,
Steinbacher, Derek M.
,
Jakus, Adam E.
in
Bioreactors
,
Bone and Bones - blood supply
,
Bone and Bones - chemistry
2018
Vascularization of engineered bone tissue is critical for ensuring its survival after implantation. In vitro pre-vascularization of bone grafts with endothelial cells is a promising strategy to improve implant survival. In this study, we pre-cultured human smooth muscle cells (hSMCs) on bone scaffolds for 3 weeks followed by seeding of human umbilical vein endothelial cells (HUVECs), which produced a desirable environment for microvasculature formation. The sequential cell-seeding protocol was successfully applied to both natural (decellularized native bone, or DB) and synthetic (3D-printed Hyperelastic “Bone” scaffolds, or HB) scaffolds, demonstrating a comprehensive platform for developing natural and synthetic-based in vitro vascularized bone grafts. Using this sequential cell-seeding process, the HUVECs formed lumen structures throughout the DB scaffolds as well as vascular tissue bridging 3D-printed fibers within the HB. The pre-cultured hSMCs were essential for endothelial cell (EC) lumen formation within DB scaffolds, as well as for upregulating EC-specific gene expression of HUVECs grown on HB scaffolds. We further applied this co-culture protocol to DB scaffolds using a perfusion bioreactor, to overcome the limitations of diffusive mass transport into the interiors of the scaffolds. Compared with static culture, panoramic histological sections of DB scaffolds cultured in bioreactors showed improved cellular density, as well as a nominal increase in the number of lumen structures formed by ECs in the interior regions of the scaffolds. In conclusion, we have demonstrated that the sequential seeding of hSMCs and HUVECs can serve to generate early microvascular networks that could further support the in vitro tissue engineering of naturally or synthetically derived bone grafts and in both random (DB) and ordered (HB) pore networks. Combined with the preliminary bioreactor study, this process also shows potential to generate clinically sized, vascularized bone scaffolds for tissue and regenerative engineering.
Journal Article
Epithelial Cell Differentiation of Human Mesenchymal Stromal Cells in Decellularized Lung Scaffolds
by
Steinbacher, Derek
,
Mendez, Julio J.
,
Ghaedi, Mahboobe
in
Adipose Tissue - cytology
,
Adult
,
Alveolar Epithelial Cells - cytology
2014
Identification of appropriate donor cell types is important for lung cell therapy and for lung regeneration. Previous studies have indicated that mesenchymal stromal cells derived from human bone marrow (hBM-MSCs) and from human adipose tissue (hAT-MSCs) may have the ability to trans-differentiate into lung epithelial cells. However, these data remain controversial. Herein, the ability of hBM-MSCs and hAT-MSCs to repopulate acellular rodent lung tissue was evaluated. hBM-MSCs and hAT-MSCs were isolated from bone marrow aspirate and lipoaspirate, respectively. Rat lungs were decellularized with CHAPS detergent, followed by seeding the matrix with hBM-MSCs and hAT-MSCs. Under appropriate culture conditions, both human MSC populations attached to and proliferated within the lung tissue scaffold. In addition, cells were capable of type 2 pneumocyte differentiation, as assessed by marker expression of surfactant protein C (pro-SPC) at the protein and the RNA level, and by the presence of lamellar bodies by transmission electron microscopy. Additionally, hAT-MSCs contributed to Clara-like cells that lined the airways in the lung scaffolds, whereas the hBM-MSCs did not. We also tested the differentiation potential of MSCs on different extracellular matrix components
in vitro
, and found that protein substrate influences MSC epithelial differentiation. Together our data show the capacity for human MSCs to differentiate toward lung epithelial phenotypes, and the possibility of using these cells for lung cell therapies and tissue engineering.
Journal Article
Processing Technique for Lipofilling Influences Adipose-Derived Stem Cell Concentration and Cell Viability in Lipoaspirate
2014
Background
Autologous fat grafting is a highly used technique in plastic and reconstructive surgery. Several fat-processing techniques have been described, with centrifugation frequently touted as the optimal method. Processing is one factor important for maximizing cell viability and adipose-derived mesenchymal stem cell (ADSC) concentrations. This study compared two methods of fat preparation (centrifugation vs Telfa-rolling) to determine which technique results in the greatest degree of cell viability and ADSC concentration.
Methods
Abdominal fat was harvested from five patients. Equal aliquots were divided and processed by both centrifugation and Telfa-rolling. Samples were analyzed for ADSC proportions via flow cytometry and cell viability using methylene blue-based cell counting. Paired
t
tests were performed on all samples, and a
P
value lower than 0.05 was considered statistically significant.
Results
Telfa-rolling processing resulted in a higher percentage of isolated ADSCs (
P
< 0.5 for 3 of 4 parameters) and a significantly higher number of viable cells (
P
< 0.05).
Conclusion
Telfa-rolling results in a higher proportion of ADSCs and greater cell viability than centrifugation for donor adipose graft preparation. Further studies are necessary to confirm whether optimal preparation translates to improved augmentation and cell take at the recipient site.
Level of Evidence IV
This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors
www.springer.com/00266
.
Journal Article
Mutations in TFAP2B and previously unimplicated genes of the BMP, Wnt, and Hedgehog pathways in syndromic craniosynostosis
by
Rodriguez, Eduardo D.
,
Steinbacher, Derek M.
,
Islam, Barira
in
Adolescent
,
alpha Catenin - genetics
,
AP-2 protein
2019
Craniosynostosis (CS) is a frequent congenital anomaly featuring the premature fusion of 1 or more sutures of the cranial vault. Syndromic cases, featuring additional congenital anomalies, make up 15% of CS. While many genes underlying syndromic CS have been identified, the cause of many syndromic cases remains unknown. We performed exome sequencing of 12 syndromic CS cases and their parents, in whom previous genetic evaluations were unrevealing. Damaging de novo or transmitted loss of function (LOF) mutations were found in 8 genes that are highly intolerant to LOF mutation (P = 4.0 × 10−8); additionally, a rare damaging mutation in SOX11, which has a lower level of intolerance, was identified. Four probands had rare damaging mutations (2 de novo) in TFAP2B, a transcription factor that orchestrates neural crest cell migration and differentiation; this mutation burden is highly significant (P = 8.2 × 10−12). Three probands had rare damaging mutations in GLI2, SOX11, or GPC4, which function in the Hedgehog, BMP, and Wnt signaling pathways; other genes in these pathways have previously been implicated in syndromic CS. Similarly, damaging de novo mutations were identified in genes encoding the chromatin modifier KAT6A, and CTNNA1, encoding catenin α-1. These findings establish TFAP2B as a CS gene, have implications for assessing risk to subsequent children in these families, and provide evidence implicating other genes in syndromic CS. This high yield indicates the value of performing exome sequencing of syndromic CS patients when sequencing of known disease loci is unrevealing.
Journal Article
Osteogenic Performance of Donor-Matched Human Adipose and Bone Marrow Mesenchymal Cells Under Dynamic Culture
by
Wu, Wei
,
Le, Andrew V.
,
Steinbacher, Derek M.
in
Adipose Tissue - cytology
,
Adult
,
Alkaline Phosphatase - metabolism
2015
Adipose-derived mesenchymal cells (ACs) and bone marrow-derived mesenchymal cells (BMCs) have been widely used for bone regeneration and can be seeded on a variety of rigid scaffolds. However, to date, a direct comparison of mesenchymal cells (MC) harvested from different tissues from the same donor and cultured in identical osteogenic conditions has not been investigated. Indeed, it is unclear whether marrow-derived or fat-derived MC possess intrinsic differences in bone-forming capabilities, since within-patient comparisons have not been previously done. This study aims at comparing ACs and BMCs from three donors ranging in age from neonatal to adult. Matched cells from each donor were studied in three distinct bioreactor settings, to determine the best method to create a viable osseous engineered construct. Human ACs and BMCs were isolated from each donor, cultured, and seeded on decellularized porcine bone (DCB) constructs. The constructs were then subjected to either static or dynamic (stirring or perfusion) bioreactor culture conditions for 7–21 days. Afterward, the constructs were analyzed for cell adhesion and distribution and osteogenic differentiation. ACs demonstrated higher seeding efficiency than BMCs. However, static and dynamic culture significantly increased BMCs proliferation more than ACs. In all conditions, BMCs demonstrated stronger osteogenic activity as compared with ACs, through higher alkaline phosphatase activity and gene expression for various bony markers. Conversely, ACs expressed more collagen I, which is a nonspecific matrix molecule in most connective tissues. Overall, dynamic bioreactor culture conditions enhanced osteogenic gene expression in both ACs and BMCs. Scaffolds seeded with BMCs in dynamic stirring culture conditions exhibit the greatest osteogenic proliferation and function
in vitro
, proving that marrow-derived MC have superior bone-forming potential as compared with adipose-derived cells.
Journal Article