Mesenchymal Stem Cell Seeded Nanofibrous Laminates Mimic the Multi-Scale Form and Function of the Annulus Fibrosus

2009 ◽  
Author(s):  
Nandan K. Nerurkar ◽  
Sounok Sen ◽  
Emily E. Wible ◽  
Jeffrey B. Stambough ◽  
Dawn M. Elliott ◽  
...  
Keyword(s):  
Annulus Fibrosus ◽  
Form And Function ◽  
Multi Scale ◽  
Aligned Arrays ◽  
Tensile Response ◽  
Nanofibrous Scaffolds ◽  
Multiple Length Scales ◽  
Spine Function ◽  
And Function ◽  
High Degree

The annulus fibrosus (AF) of the intervertebral disc is a multi-lamellar fibrocartilage that, together with the nucleus pulposus, confers mechanical support and flexibility to the spine. Function of the AF is predicated on a high degree of structural organization over multiple length scales: aligned collagen fibers reside within each lamella, and the direction of alignment alternates between adjacent lamellae from +30° to −30° with respect to the transverse axis of the spine. Electrospinning permits fabrication of scaffolds consisting of aligned arrays of nanofibers, and has proven effective for directing the alignment of both cells and extracellular matrix (ECM) deposition [1–3]. We recently employed electrospinning to engineer the primary functional unit of the AF, a single lamella [4]. However, it remains a challenge to engineer a multi-lamellar tissue that replicates the cross-ply fiber architecture of the native AF. Moreover, relatively few studies have considered functional properties of engineered AF, and, when measured, tensile properties of these constructs have been inferior to native AF [4]. In this study, mesenchymal stem cells (MSCs) were seeded onto aligned nanofibrous scaffolds organized into bi-lamellar constructs with opposing or parallel fiber orientations, and their functional maturation was evaluated with time. Additionally, we determined a novel role for inter-lamellar ECM in reinforcing the tensile response of bilayers, and confirmed this mechanism by testing acellular bilayers with controllable interface properties.

Modeling Inter-Lamellar Interactions in Angle-Ply Nanofibrous Biologic Laminates for Annulus Fibrosus Tissue Engineering

2010 ◽  
Author(s):  
Nandan L. Nerurkar ◽  
Robert L. Mauck ◽  
Dawn M. Elliott
Keyword(s):  
Tissue Engineering ◽  
Annulus Fibrosus ◽  
Uniaxial Extension ◽  
Direct Consequence ◽  
Continuum Models ◽  
Form And Function ◽  
Multiple Length Scales ◽  
And Function ◽  
High Degree

Function of the annulus fibrosus (AF) of the intervertebral disc is predicated on a high degree of structural organization over multiple length scales. Recently, we have employed aligned electrospun scaffolds to engineer nanofibrous biologic laminates that replicate the form and function of the AF [1]. Further, we determined that interlamellar shearing — a direct consequence of the +/−30° angle-ply architecture — plays an important role in reinforcing the tensile response of these materials (Fig. 1). Although we have utilized fiber-reinforced continuum models to characterize the evolving mechanics of single-lamellar AF constructs with in vitro culture [2, 3], these models are not capable of capturing the interlamellar interactions observed in bi-lamellar constructs. Indeed, continuum models of the native AF typically do not account for the organization of fiber populations into discrete, alternating planes of alignment, and so these models, too, do not account for inter-lamellar shearing interactions [4–6]. Therefore, in the present work we propose a novel constitutive model for the reinforcing role of interlamellar shearing during uniaxial extension of angle-ply biologic laminates and employ this model to evaluate the functional evolution of bilayers for AF tissue engineering.

Herbaceous monocot plant form and function along a tropical rain-forest light gradient: a reversal of dicot strategy

2009 ◽  
Vol 25 (1) ◽  
pp. 103-106 ◽  
Author(s):  
Nathan G. Swenson
Keyword(s):  
Tropical Forests ◽  
Environmental Gradients ◽  
Plant Performance ◽  
Seed Plants ◽  
Form And Function ◽  
Light Gradient ◽  
Whole Plant ◽  
Plant Form ◽  
And Function ◽  
High Degree

Whole plant form and function vary spectacularly across the seed plants. In recent years, plant evolutionary ecologists have begun to document this diversity on large geographic scales by analysing ‘functional traits’ that are indicative of whole plant performance across environmental gradients (Swenson & Enquist 2007, Wright et al. 2004). Despite the high degree of functional diversity in tropical forests, convergence in function does occur locally along successional or light gradients (Bazzaz & Pickett 1980, Swaine & Whitmore 1988).

scholarly journals Nanofibrous biologic laminates replicate the form and function of the annulus fibrosus

2009 ◽  
Vol 8 (12) ◽  
pp. 986-992 ◽  
Author(s):  
Nandan L. Nerurkar ◽  
Brendon M. Baker ◽  
Sounok Sen ◽  
Emily E. Wible ◽  
Dawn M. Elliott ◽  
...  
Keyword(s):  
Annulus Fibrosus ◽  
Form And Function ◽  
And Function

Towards intervertebral disc engineering: Bio-mimetics of form and function of the annulus fibrosus lamellae

2019 ◽  
Vol 94 ◽  
pp. 298-307 ◽  
Author(s):  
Mirit Sharabi ◽  
Shir Wertheimer ◽  
Kelly R. Wade ◽  
Fabio Galbusera ◽  
Dafna Benayahu ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Annulus Fibrosus ◽  
Form And Function ◽  
And Function

scholarly journals Silk-based multilayered angle-ply annulus fibrosus construct to recapitulate form and function of the intervertebral disc

2017 ◽  
Vol 115 (3) ◽  
pp. 477-482 ◽  
Author(s):  
Bibhas K. Bhunia ◽  
David L. Kaplan ◽  
Biman B. Mandal
Keyword(s):  
Intervertebral Disc ◽  
Annulus Fibrosus ◽  
Human Mesenchymal Stem Cells ◽  
Collagen Type I ◽  
Hierarchical Architecture ◽  
Elastic Fibers ◽  
Type I ◽  
Form And Function ◽  
Tissue Organization ◽  
And Function

Recapitulation of the form and function of complex tissue organization using appropriate biomaterials impacts success in tissue engineering endeavors. The annulus fibrosus (AF) represents a complex, multilamellar, hierarchical structure consisting of collagen, proteoglycans, and elastic fibers. To mimic the intricacy of AF anatomy, a silk protein-based multilayered, disc-like angle-ply construct was fabricated, consisting of concentric layers of lamellar sheets. Scanning electron microscopy and fluorescence image analysis revealed cross-aligned and lamellar characteristics of the construct, mimicking the native hierarchical architecture of the AF. Induction of secondary structure in the silk constructs was confirmed by infrared spectroscopy and X-ray diffraction. The constructs showed a compressive modulus of 499.18 ± 86.45 kPa. Constructs seeded with porcine AF cells and human mesenchymal stem cells (hMSCs) showed ∼2.2-fold and ∼1.7-fold increases in proliferation on day 14, respectively, compared with initial seeding. Biochemical analysis, histology, and immunohistochemistry results showed the deposition of AF-specific extracellular matrix (sulfated glycosaminoglycan and collagen type I), indicating a favorable environment for both cell types, which was further validated by the expression of AF tissue-specific genes. The constructs seeded with porcine AF cells showed ∼11-, ∼5.1-, and ∼6.7-fold increases in col Iα 1, sox 9, and aggrecan genes, respectively. The differentiation of hMSCs to AF-like tissue was evident from the enhanced expression of the AF-specific genes. Overall, the constructs supported cell proliferation, differentiation, and ECM deposition resulting in AF-like tissue features based on ECM deposition and morphology, indicating potential for future studies related to intervertebral disc replacement therapy.

scholarly journals Critical Issues in Modelling Lymph Node Physiology

2016 ◽  
Author(s):  
Dmitry Grebennikov ◽  
Raoul van Loon ◽  
Mario Novkovic ◽  
Lucas Onder ◽  
Rostislav Savinkov ◽  
...  
Keyword(s):  
Reticular Cell ◽  
Vascular Networks ◽  
Microvascular Networks ◽  
Multi Scale ◽  
3D Geometry ◽  
Fibroblastic Reticular Cell ◽  
Critical Issues ◽  
And Function ◽  
High Degree ◽  
Flow Study

In this study we discuss critical issues in modelling the structure and function of lymph nodes (LNs), with emphasis on how LN physiology is related to its multi-scale structural organization. In addition to macroscopic domains such as B-cell follicles and the T cell zone, there are vascular networks which play a key role in the delivery of information to the inner parts of the LN, i.e., the conduit and blood microvascular networks. We propose object-oriented computational algorithms to model the 3D geometry of the fibroblastic reticular cell (FRC) network and the microvasculature. Assuming that a conduit cylinder is densely packed with collagen fibers, the computational flow study predicted that the diffusion should be a dominating process in mass transport than convective flow. The geometry models are used to analyze the lymph flow properties through the conduit network in unperturbed- and damaged states of the LN. The analysis predicts that elimination of up to 60–90 % of edges is required to stop the lymph flux. This result suggests a high degree of functional robustness of the network.

FEISEM, Form and Function in the Nuclear Pore Complex

1998 ◽  
Vol 4 (S2) ◽  
pp. 958-959
Author(s):  
T.D. Allen ◽  
G. R. Bcnnion ◽  
S. A. Rutherford ◽  
E. Kiscleva ◽  
M. W. Goldberg
Keyword(s):  
Nuclear Pore Complex ◽  
Considerable Increase ◽  
Structural Complexity ◽  
Nuclear Pore ◽  
Molecular Architecture ◽  
Structural Elements ◽  
Form And Function ◽  
Import And Export ◽  
And Function ◽  
High Degree

Recent initiatives have resulted in a considerable increase in our understanding of the structure of the nuclear pore complex (NPC). The biochemical factors involved in both import and export have been rapidly characterised, with steady progress in the molecular dissection of the structural elements of the NPC, which is a unit of considerable molecular architecture (MW 125 kD), comprising an estimated 50- 100 different proteins. Despite this progress, the crucial molecular interactions involved in the mechanics of transport through the central transporter of the NPC remain unclear. NPC structure in Diptera, fish, (Fig 1) amphibians, birds and mammals shows a high degree of evolutionary conservation. 3D reconstructions of isolated yeast NPCs, show that the core structure is very similar to ‘higher’ organisms, but peripheral structures may be considerably reduced in structural complexity (1).Individual NPC components have been accessed in FEISEM by a variety of methods, including proteolysis,

Scanning tunneling microscopy (STM) of DNA and RNA

1989 ◽  
Vol 47 ◽  
pp. 34-35
Author(s):  
Patricia G. Arscott ◽  
Gil Lee ◽  
Victor A. Bloomfield ◽  
D. Fennell Evans
Keyword(s):  
Molecular Structures ◽  
Inorganic Materials ◽  
Resolving Power ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Form And Function ◽  
Dna And Rna ◽  
Calf Thymus ◽  
And Function ◽  
The Relationship

STM is one of the most promising techniques available for visualizing the fine details of biomolecular structure. It has been used to map the surface topography of inorganic materials in atomic dimensions, and thus has the resolving power not only to determine the conformation of small molecules but to distinguish site-specific features within a molecule. That level of detail is of critical importance in understanding the relationship between form and function in biological systems. The size, shape, and accessibility of molecular structures can be determined much more accurately by STM than by electron microscopy since no staining, shadowing or labeling with heavy metals is required, and there is no exposure to damaging radiation by electrons. Crystallography and most other physical techniques do not give information about individual molecules.We have obtained striking images of DNA and RNA, using calf thymus DNA and two synthetic polynucleotides, poly(dG-me5dC)·poly(dG-me5dC) and poly(rA)·poly(rU).

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