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James J. Hickman - One of the best experts on this subject based on the ideXlab platform.
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Differentiation of Intrafusal fibers from human induced pluripotent stem cells
ACS chemical neuroscience, 2020Co-Authors: Alisha Colon, Agnes Badu-mensah, Xiufang Guo, Arindom Goswami, James J. HickmanAbstract:Human-based "body-on-a-chip" technology provides powerful platforms in developing models for drug evaluation and disease evaluations in phenotypic models. Induced pluripotent stem cells (iPSCs) are ideal cell sources for generating different cell types for these in vitro functional systems and recapitulation of the neuromuscular reflex arc would allow for the study of patient specific neuromuscular diseases. Regarding relevant afferent (Intrafusal fibers, sensory neurons) and efferent (extrafusal fibers, motoneurons) cells, in vitro differentiation of Intrafusal fiber from human iPSCs has not been established. This work demonstrates a protocol for inducing an enrichment of Intrafusal bag fibers from iPSCs using morphological analysis and immunocytochemistry. Phosphorylation of the ErbB2 receptors and S46 staining indicated a 3-fold increase of total Intrafusal fibers further confirming the efficiency of the protocol. Integration of induced Intrafusal fibers would enable more accurate reflex arc models and application of this protocol on patient iPSCs would allow for patient-specific disease modeling.
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tissue engineering the mechanosensory circuit of the stretch reflex arc with human stem cells sensory neuron innervation of Intrafusal muscle fibers
Biomaterials, 2017Co-Authors: Xiufang Guo, Maria Stancescu, Alisha Colon, Nesar Akanda, Severo Spradling, Candace Martin, James J. HickmanAbstract:Muscle spindles are sensory organs embedded in the belly of skeletal muscles that serve as mechanoreceptors detecting static and dynamic information about muscle length and stretch. Through their connection with proprioceptive sensory neurons, sensation of axial body position and muscle movement are transmitted to the central nervous system. Impairment of this sensory circuit causes motor deficits and has been linked to a wide range of diseases. To date, no defined human-based in vitro model of the proprioceptive sensory circuit has been developed. The goal of this study was to develop a human-based in vitro muscle sensory circuit utilizing human stem cells. A serum-free medium was developed to drive the induction of Intrafusal fibers from human satellite cells by actuation of a neuregulin signaling pathway. Both bag and chain Intrafusal fibers were generated and subsequently validated by phase microscopy and immunocytochemistry. When co-cultured with proprioceptive sensory neurons derived from human neuroprogenitors, mechanosensory nerve terminal structural features with Intrafusal fibers were demonstrated. Most importantly, patch-clamp electrophysiological analysis of the Intrafusal fibers indicated repetitive firing of human Intrafusal fibers, which has not been observed in human extrafusal fibers.
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Tissue engineering the mechanosensory circuit of the stretch reflex arc: sensory neuron innervation of Intrafusal muscle fibers.
Biomaterials, 2010Co-Authors: John W. Rumsey, Mainak Das, Maria Stancescu, Abhijeet Bhalkikar, James J. HickmanAbstract:Abstract The sensory circuit of the stretch reflex arc, composed of specialized Intrafusal muscle fibers and type Ia proprioceptive sensory neurons, converts mechanical information regarding muscle length and stretch to electrical action potentials and relays them to the central nervous system. Utilizing a non-biological substrate, surface patterning photolithography and a serum-free medium formulation a co-culture system was developed that facilitated functional interactions between Intrafusal muscle fibers and sensory neurons. The presence of annulospiral wrappings (ASWs) and flower-spray endings (FSEs), both physiologically relevant morphologies in sensory neuron-Intrafusal fiber interactions, were demonstrated and quantified using immunocytochemistry. Furthermore, two proposed components of the mammalian mechanosensory transduction system, BNaC1 and PICK1, were both identified at the ASWs and FSEs. To verify functionality of the mechanoreceptor elements the system was integrated with a MEMS cantilever device, and Ca 2+ currents were imaged along the length of an axon innervating an Intrafusal fiber when stretched by cantilever deflection. This system provides a platform for examining the role of this mechanosensory complex in the pathology of myotonic and muscular dystrophies, peripheral neuropathy, and spasticity inducing diseases like Parkinson’s. These studies will also assist in engineering fine motor control for prosthetic devices by improving our understanding of mechanosensitive feedback.
J. M. Schröder - One of the best experts on this subject based on the ideXlab platform.
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Scanning electron microscopic study of denervated and reinnervated Intrafusal muscle fibers in rats
Muscle & nerve, 1992Co-Authors: Dieler R, Völker A, J. M. SchröderAbstract:Isolated muscle spindles from lower lumbrical muscles of rats were used to study the 3-dimensional organization of Intrafusal structures by scanning electron microscopy following (a) complete denervation, (b) reinnervation after a single crush lesion of the sciatic nerve, or (c) reinnervation after transection and immediate suture of this nerve. One week after complete denervation, previous sites of Intrafusal motor endplates were transformed into sarcolemmal ovoid bulges. These bulges persisted in denervated muscle spindles up to 12 weeks. Regenerated motor nerve endings were detected on Intrafusal muscle fibers 1 month, and thereafter following sciatic nerve crush injuries, and 3 months and later following transection and suture of the nerve. Furthermore, 3 different types of subsynaptic areas of motor nerve terminals were observed. The scanning electron microscopic technique also allowed visualization of splitting and fusion of Intrafusal muscle fibers. The findings are discussed in view of their possible functional implications.
Alfred Maier - One of the best experts on this subject based on the ideXlab platform.
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Morphological variability and specializations in bovine extraocular muscle spindles
Annals of Anatomy-anatomischer Anzeiger, 2000Co-Authors: Alfred MaierAbstract:Summary Bovine extraocular muscles were examined to determine whether the structure of their muscle spindles was notably different from those commonly encountered in mammalian limb muscles. Extraocular muscle spindles on the whole were shorter, and Intrafusal fiber counts/spindle were more variable than in somatic muscles. No pronounced nuclear bags were seen in Intrafusal fibers. Based on cross-sectional areas, Intrafusal fibers in extraocular muscles could be loosely categorized as small or large types. Small fibers expressed more neonatal/fast myosin heavy chain and less embryonic myosin heavy chain than large fibers. When incubated for myosin ATPase, about 70% of the large fibers and 15% of the small fibers in spindles presented profiles that were characteristic of type I extrafusal fibers, and not of nuclear bag or nuclear chain fibers. The ratio of number of small Intrafusal fibers to number of large Intrafusal fibers in extraocular spindles was on average greater than the ratio of nuclear chain fibers to nuclear bag fibers that is typical for limb spindles of rodents and cats. Structural modifications at muscle spindle sensory regions, extrafusal-like fibers and Intrafusal-like fibers with few equatorial nuclei and many myofibrils, may produce distinct afferent signals that are appropriate for sensorimotor integration in the specialized extraocular muscles.
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Sensory innervation of myosin heavy chain-based types of chicken Intrafusal fiber.
European journal of morphology, 1998Co-Authors: Alfred MaierAbstract:Chicken Intrafusal fibers that had been categorized as slow or fast contracting by their reactions with monoclonal antibodies against myosin heavy chains (MHC) at polar regions were examined at the equator and neighboring juxtaequator to determine if fiber type-specific morphologies were also present at the sensory region. The parameters chosen for examination were contractile filaments, distribution of acetylcholinesterase and sensory innervation. Evaluation of acetylcholinesterase was included to define the proximal limit of motor terminal distribution. At the equator actin was primarily restricted to a thin layer beneath myosensory junctions. Myosin heavy chains at the equator and the juxtaequator were more evenly distributed. Although absent from the synaptic side of the sensory region, acetylcholinesterase activity was present on the extrasynaptic side. Plots of diameters of sensory axon collaterals and of sensory endings yielded continuous spectra instead of distinct peaks. Taken together, these features indicated a uniform equatorial morphology. However, sensory terminals to fast Intrafusal fibers were longer and narrower than those to slow Intrafusal fibers, and typically more terminals impinged on fast than on slow Intrafusal fibers. Moreover, in the larger spindles short sensory terminals were most prevalent near the equatorial-juxtaequatorial junction, the region where in mammalian Intrafusal fibers secondary sensory axons make contact. The differences seen in sizes and distributions of terminals suggest that, despite the lack of type-specific morphologies at the sensory region of chicken Intrafusal fiber types, some level of functional separation is maintained there.
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Extracellular matrix and transmembrane linkages at the termination of Intrafusal fibers and the outer capsule in chicken muscle spindles.
Journal of morphology, 1996Co-Authors: Alfred MaierAbstract:Attachments of Intrafusal fibers and of the outer spindle capsule at the far polar region were examined by immunohistochemistry in serially sectioned chicken leg muscles. Patterns of distribution of connective tissues and intracellular filaments suggest that, in this segment of the muscle spindle, Intrafusal fibers bind laterally with the capsule. Contrary to extrafusal fibers at myotendinous junctions, folded plasmalemmas at the ends of Intrafusal fibers were rare. Thus, there was little end-to-end interlocking between Intrafusal fibers and the extracellular matrix. The tapered contours of terminating Intrafusal fibers resembled those of extrafusal fibers which end in fascicles without tendinous connections. At points where the distal portions of Intrafusal fibers closely adjoined and overlapped extrafusal fibers, alpha-actinin, vinculin, filamin, talin, beta 1 integrin, spectrin, and dystrophin occurred with moderate to great frequency. It is generally accepted that these compounds are links in molecular chains that extend from the intracellular space across cell membranes to the extracellular matrix. Their location along substantial lengths of extrafusal fibers, distal capsule, and terminating Intrafusal fibers suggests the presence of numerous transverse connections between elements of the terminal portion of the spindle and nonspindle tissues. Hence, it is likely that forces monitored by chicken spindles in muscles undergoing length changes are transferred from extrafusal fibers and extracellular matrix to the receptors in large part via lateral shear instead of by longitudinal tension.
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Fiber-type compositions in postnatal chicken muscle spindles with low Intrafusal fiber counts and their developmental significance.
Journal of morphology, 1995Co-Authors: Alfred MaierAbstract:The fiber-type composition of postnatal chicken leg muscle spindles with from one to four Intrafusal fibers was examined in sections incubated with monoclonal antibodies against fast and slow myosin heavy chains. In monofibral spindles the lone Intrafusal fiber was almost always fast. In duofibral spindles usually one slow and one fast fiber were present. Trifibral spindles most often displayed two fast and one slow fiber, whereas quadrofibral receptors characteristically contained two slow and two fast fibers. Earlier results showed that the primary Intrafusal myotube in nascent spindles has almost always a fast myosin heavy chain profile and that the proportion of slow myotubes and fibers increases as Intrafusal fiber bundles grow in size. Data from postnatal chicken leg muscles collected here suggest that up to the first four fibers this proportional increase can be largely accounted for if consecutive Intrafusal fibers arise in a fast-slow-fast-slow sequence. The late recognition during myogenesis of primary Intrafusal myotubes and their fast myosin heavy chain profiles warrant exploring if nascent chicken muscles spindles are first seeded by fast fetal myoblasts. © 1995 Wiley-Liss, Inc.
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Type and regional diversity in the distribution of myosin heavy chains in chicken Intrafusal muscle fibers
Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 1994Co-Authors: Alfred MaierAbstract:Background: Chicken Intrafusal fibers were classifed on the basis of their myosin heavy chain (MHC) composition, which was compared to that of mammalian nuclear bag and nuclear chain types. Methods: Immunoreactivities of Intrafusal fibers from leg muscles of 8-week-old chickens were evaluated in serial cross-sections after incubation with monoclonal antibodies against slow-twitch, slow-tonic, or fast-twitch MHC and fast muscle C-protein. Results: Four categories of slow Intrafusal fiber could be distinguished on the basis of differential expression of slow-twitch and slow-tonic MHC. Segregation into types was most evident at the motor axon supplied pole, followed by the sensory region of the equator. Fiber types were least distinct at the juxtaequator where sensory and motor axons meet. Intrafusal fibers negative for slow myosins reacted with anti-fast myosins. Fast fibers were best viewed as a single group without subdivisions. Immunostaining for fast muscle C-protein paralleled in large part reactivities for neonatal/fast MHC, indicating that proteins other than MHC are useful fiber type markers. Conclusions: Despite regional changes along the length of Intrafusal fibers and some variation within fiber types, the concept of separate MHC-based fiber types was valid as long as typing of fibers was restricted to the proximal polar region. Comparisons of MHC profiles revealed similarities between chicken fast Intrafusal fibers and mammalian nuclear chain fibers and between some chicken slow Intrafusal fibers and mammalian nuclear bag fibers. © 1994 Wiley-Liss, Inc.
Dieler R - One of the best experts on this subject based on the ideXlab platform.
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Scanning electron microscopic study of denervated and reinnervated Intrafusal muscle fibers in rats
Muscle & nerve, 1992Co-Authors: Dieler R, Völker A, J. M. SchröderAbstract:Isolated muscle spindles from lower lumbrical muscles of rats were used to study the 3-dimensional organization of Intrafusal structures by scanning electron microscopy following (a) complete denervation, (b) reinnervation after a single crush lesion of the sciatic nerve, or (c) reinnervation after transection and immediate suture of this nerve. One week after complete denervation, previous sites of Intrafusal motor endplates were transformed into sarcolemmal ovoid bulges. These bulges persisted in denervated muscle spindles up to 12 weeks. Regenerated motor nerve endings were detected on Intrafusal muscle fibers 1 month, and thereafter following sciatic nerve crush injuries, and 3 months and later following transection and suture of the nerve. Furthermore, 3 different types of subsynaptic areas of motor nerve terminals were observed. The scanning electron microscopic technique also allowed visualization of splitting and fusion of Intrafusal muscle fibers. The findings are discussed in view of their possible functional implications.
Lars-eric Thornell - One of the best experts on this subject based on the ideXlab platform.
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Fibre typing of Intrafusal fibres
Journal of Anatomy, 2015Co-Authors: Lars-eric Thornell, Lena Carlsson, Per-olof Eriksson, Catharina Österlund, Per Stål, Fatima Pedrosa-domellöfAbstract:The first descriptions of muscle spindles with Intrafusal fibres containing striated myofibrils and nervous elements were given approximately 150 years ago. It took, however, another 100 years to establish the presence of two types of Intrafusal muscle fibres: nuclear bag and nuclear chain fibres. The present paper highlights primarily the contribution of Robert Banks in fibre typing of Intrafusal fibres: the confirmation of the principle of two types of nuclear bag fibres in mammalian spindles and the variation in occurrence of a dense M-band along the fibres. Furthermore, this paper summarizes how studies from the Umea University group (Laboratory of Muscle Biology in the Department of Integrative Medical Biology) on fibre typing and the structure and composition of M-bands have contributed to the current understanding of muscle spindle complexity in adult humans as well as to muscle spindle development and effects of ageing. The variable molecular composition of the Intrafusal sarcomeres with respect to myosin heavy chains and M-band proteins gives new perspectives on the role of the Intrafusal myofibrils as stretch-activated sensors influencing tension/stiffness and signalling to nuclei.
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Intrafusal fiber type composition of muscle spindles in the first human lumbrical muscle
Acta Neuropathologica, 2003Co-Authors: Tomáš Soukup, Fatima Pedrosa-domellöf, Lars-eric ThornellAbstract:We studied muscle spindles in the first lumbrical muscle of adult humans using myofibrillar ATPase (mATPase) activity. We found that muscle spindles exhibited a marked variability with respect to the number, position, length and detailed histochemical features of nuclear bag1, nuclear bag2 and nuclear chain fibers. Regarding mATPase activity, the nuclear bag2 fibers displayed lower alkali-stable mATPase activity along their length and many nuclear bag1 fibers tended to have lower acid-stable activity in the outer B region, whereas nuclear chain fibers exhibited medium acid-stable mATPase activity at pH 4.6. Almost 10% of spindle fibers displayed atypical features, as they were either located only at one spindle pole or exhibited mixed characteristics at either pole. The number of Intrafusal fibers per spindle varied between 8 and 24. Strikingly, only 2 pairs from 22 muscle spindles had identical allotments of their Intrafusal fibers. Muscle spindles in the first human lumbrical muscle contained more Intrafusal fibers (12.3 ± 4 per spindle on average) and especially relatively more nuclear bag fibers compared to other human skeletal muscles. Since each spindle apparently represents a unique morphological and physiological entity, the observed variability in the number and characteristics of Intrafusal fibers in the first human lumbrical muscle likely reflects a wide range of finely tuned muscle spindle responses.
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Unusual Intrafusal fibres in human muscle spindles.
Physiological research, 1999Co-Authors: T. Soukup, Lars-eric ThornellAbstract:We have studied the morphology and pattern of expression of myosin heavy chain (MHC) isoforms of Intrafusal fibres in a human first lumbrical muscle. Each Intrafusal fibre type, namely nuclear bag1, nuclear bag2 and nuclear chain fibres, had a distinct MHC composition and distribution of different MHC isoforms along the whole length of Intrafusal fibres. However, most muscle spindles analyzed also contained one or several Intrafusal fibres exhibiting an extrafusal or mixed pattern of immunoreactivity which did not correspond to any of the described Intrafusal fibre types. We conclude that the latter fibres do not represent new Intrafusal fibre types, but their morphology and expression of MHC merely reflects the differences in their innervation owing to their unusual localization at the edge or outside the axial bundle of Intrafusal fibres.
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Expression of myosin heavy chain (MyHC) isoforms in rat Intrafusal muscle fibres after neonatal deefferentation and subsequent denervation.
General physiology and biophysics, 1999Co-Authors: T. Soukup, Jirmanová I, Mrácková K, Zacharová G, Lars-eric ThornellAbstract:The analysis of developing Intrafusal fibres is not feasible in the absence of primary sensory axons, as neonatal denervation leads to the disintegration of muscle spindles. On the other hand, neonatal deefferentation does not arrest their differentiation and, moreover, it leads to the neomyogenesis of supernumerary Intrafusal profiles. If the sciatic nerve was sectioned in 4-week-old rats deefferented at the birth, muscle spindles survived, the neomyogenesis proceeded and the denervated Intrafusal fibres expressed the spindle specific slow tonic (STO) MyHC. The expression of MyHC pattern in individual fibres and the differentiation of the fibre type characteristics were, however, less obvious compared to the control or deefferented spindles. The newly formed Intrafusal profiles (which differentiated from satellite cells in the absence of innervation) expressed the STO MyHC particularly when they developed in a spatial relation to nuclear bag fibres.
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expression of myosin heavy chain isoforms in regenerated muscle spindle fibres after muscle grafting in young and adult rats plasticity of Intrafusal satellite cells
Differentiation, 1998Co-Authors: T. Soukup, Lars-eric ThornellAbstract:Satellite cells are the myogenic precursor cells of postnatal skeletal muscles. After muscle injury they can proliferate, differentiate, fuse and form myofibres. We have analysed regeneration of distinctly different types of Intrafusal fibres in rat muscle spindles. We have introduced the new technique of heterochronous allotransplantation and compared it with the previously used standard autografting method. The allotransplantation method enables one to graft muscles from very young animals; we have used the extensor digitorum longus (EDL) muscles from 2- to 28-day-old rats, which were grafted into EDL muscles of adult inbred recipients. The regenerated “Intrafusal” fibres did not express the spindle-specific slow tonic and alpha cardiac-like myosin heavy chain (MyHC) isoforms and they did not exhibit the dual mATPase reaction typical of the nuclear bag2 fibres and the characteristic regional differences in MyHC expression and in the mATPase reaction of nuclear bag1 and nuclear bag2 fibres. On the other hand, they expressed either fast twitch or slow twitch/beta cardiac MyHC isoforms and exhibited an alkali or acid stable mATPase reaction along their whole length, like extrafusal fast type 2 and slow type 1 muscle fibres, respectively. In all regenerated muscle spindles only motor, but no sensory axons were found. More than 85% of muscle spindles in our sample contained regenerated spindle fibres of the same extrafusal fibre type (either type 2 or type 1), in contrast to control muscle spindles, which always contained Intrafusal fibres of three different Intrafusal fibre types (nuclear bag1, nuclear bag2 and nuclear chain fibres). There were no differences in MyHC expression and mATPase activity between spindle fibres regenerated in grafts taken from young rats of various ages or between allotransplanted and autotransplanted EDL muscles. The present results demonstrate that regenerated “Intrafusal” fibres resemble, according to MyHC expression, extrafusal fast or slow muscle fibres. It can thus be concluded that Intrafusal satellite cells derived from distinctly different nuclear bag1, nuclear bag2 and nuclear chain fibres show great plasticity, as their MyHC expression can be respecified towards the extrafusal muscle fibre phenotype by foreign alpha-motor innervation.