Limits...
Biodegradable biomatrices and bridging the injured spinal cord: the corticospinal tract as a proof of principle.

Joosten EA - Cell Tissue Res. (2012)

Bottom Line: These advances are evaluated in this review with special emphasis on the regeneration of the corticospinal tract.The corticospinal tract is often considered the ultimate challenge in demonstrating whether a repair strategy has been successful in the regeneration of the injured mammalian spinal cord.The extensive know-how of factors and cells involved in the development of the corticospinal tract, and the advances made in material science and tissue engineering technology, have provided the foundations for the optimization of the biomatrices needed for repair.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Pain Management and Research Center, Maastricht University Medical Hospital, Maastricht, The Netherlands. b.joosten@maastrichtuniversity.nl

ABSTRACT
Important advances in the development of smart biodegradable implants for axonal regeneration after spinal cord injury have recently been reported. These advances are evaluated in this review with special emphasis on the regeneration of the corticospinal tract. The corticospinal tract is often considered the ultimate challenge in demonstrating whether a repair strategy has been successful in the regeneration of the injured mammalian spinal cord. The extensive know-how of factors and cells involved in the development of the corticospinal tract, and the advances made in material science and tissue engineering technology, have provided the foundations for the optimization of the biomatrices needed for repair. Based on the findings summarized in this review, the future development of smart biodegradable bridges for CST regrowth and regeneration in the injured spinal cord is discussed.

Show MeSH

Related in: MedlinePlus

Schematic representation of outgrowth and guidance factors involved in the developing corticospinal tract in rat spinal cord. Vimentin immunoreactive astroglial cells (a) are situated in longitudinal tiers with their processes perpendicular to the outgrowing CST pioneer fibers and their growth cones (gc) (Joosten and Gribnau 1989a, b). The embryonic form of N-CAM is present on the growth cones of the pioneer CST fibers. The later-arriving CST fibers are guided by the cell adhesion molecule L1. During spinal gray matter target innervation, mainly through the formation of so-called back-branches, a tropic factor, probably NT-3, is released by either the CST target (inter)-neurons (in) or astroglial cells (a). Adapted from (Joosten 1997), with permission
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3375422&req=5

Fig1: Schematic representation of outgrowth and guidance factors involved in the developing corticospinal tract in rat spinal cord. Vimentin immunoreactive astroglial cells (a) are situated in longitudinal tiers with their processes perpendicular to the outgrowing CST pioneer fibers and their growth cones (gc) (Joosten and Gribnau 1989a, b). The embryonic form of N-CAM is present on the growth cones of the pioneer CST fibers. The later-arriving CST fibers are guided by the cell adhesion molecule L1. During spinal gray matter target innervation, mainly through the formation of so-called back-branches, a tropic factor, probably NT-3, is released by either the CST target (inter)-neurons (in) or astroglial cells (a). Adapted from (Joosten 1997), with permission

Mentions: The outgrowth of the corticospinal tract (CST) into the spinal cord of the rat is characterized by two phases, which both occur postnatally: a white matter tract formation on the one hand and the spinal gray matter target innervations on the other. Both phases are closely related and have been shown in various anterograde tract-tracing studies (Schreyer and Jones 1982; Joosten et al. 1987; Curfs et al. 1995; Joosten and Bar 1999). The outgrowth of main bulk of CST fibers is preceded by a relatively small number of pioneering axons with large growth cones (Gorgels et al. 1989). The majority of the CST axons follow these pioneering growth cones in tightly fasciculated bundles located in the ventralmost part of the dorsal funiculus (vDF) of the rat spinal cord. This staggered mode of outgrowth into the spinal white matter is shown in Fig. 1. After a waiting period (Donatelle 1977; Gribnau et al. 1986), the axons exit from the vDF by collateral branching in a rostro-caudal wave along the spinal cord (Kuang and Kalil 1991). Initially, these collaterals branch extensively in the gray matter, especially in the cervical and lumbar enlargements (Karimi-Abdolrezaee et al. 2002) where they finally transmit signals to muscles that control fore- and hindlimbs, respectively. This process of extensive collateral branching and arborization in the spinal gray is finally refined based on the connections made and mediated by the activity-dependent remodeling of the synaptic connections between the CST fibers and target interneurons (Ohno and Sakurai 2005). The interneurons have already then made contacts with the motoneurons in the ventral gray matter and the latter already have functional connections with the flexor and extensor muscles in fore- and hindlimbs. In view of functionality and the acquisition of voluntary movements, as this is the main function of the CST, it should be noted that learning the full complexity of locomotion is only possible if the CST is innervating not only the cervical but also the lumbar spinal cord. Then, finally, when the CST is fully grown, at the end of the third postnatal week, although myelination of fibers in the vDF may still take place (Gorgels 1990; Leenen et al.1989), the animals are able to execute very precise movements of the different muscle groups in particular in the forelimbs. This is therefore why the grasping test, which depends on the fine movements and interaction between forelimb digits, is considered a behavioral outcome of functionality of the CST in rats (Stackhouse et al. 2008).Fig. 1


Biodegradable biomatrices and bridging the injured spinal cord: the corticospinal tract as a proof of principle.

Joosten EA - Cell Tissue Res. (2012)

Schematic representation of outgrowth and guidance factors involved in the developing corticospinal tract in rat spinal cord. Vimentin immunoreactive astroglial cells (a) are situated in longitudinal tiers with their processes perpendicular to the outgrowing CST pioneer fibers and their growth cones (gc) (Joosten and Gribnau 1989a, b). The embryonic form of N-CAM is present on the growth cones of the pioneer CST fibers. The later-arriving CST fibers are guided by the cell adhesion molecule L1. During spinal gray matter target innervation, mainly through the formation of so-called back-branches, a tropic factor, probably NT-3, is released by either the CST target (inter)-neurons (in) or astroglial cells (a). Adapted from (Joosten 1997), with permission
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3375422&req=5

Fig1: Schematic representation of outgrowth and guidance factors involved in the developing corticospinal tract in rat spinal cord. Vimentin immunoreactive astroglial cells (a) are situated in longitudinal tiers with their processes perpendicular to the outgrowing CST pioneer fibers and their growth cones (gc) (Joosten and Gribnau 1989a, b). The embryonic form of N-CAM is present on the growth cones of the pioneer CST fibers. The later-arriving CST fibers are guided by the cell adhesion molecule L1. During spinal gray matter target innervation, mainly through the formation of so-called back-branches, a tropic factor, probably NT-3, is released by either the CST target (inter)-neurons (in) or astroglial cells (a). Adapted from (Joosten 1997), with permission
Mentions: The outgrowth of the corticospinal tract (CST) into the spinal cord of the rat is characterized by two phases, which both occur postnatally: a white matter tract formation on the one hand and the spinal gray matter target innervations on the other. Both phases are closely related and have been shown in various anterograde tract-tracing studies (Schreyer and Jones 1982; Joosten et al. 1987; Curfs et al. 1995; Joosten and Bar 1999). The outgrowth of main bulk of CST fibers is preceded by a relatively small number of pioneering axons with large growth cones (Gorgels et al. 1989). The majority of the CST axons follow these pioneering growth cones in tightly fasciculated bundles located in the ventralmost part of the dorsal funiculus (vDF) of the rat spinal cord. This staggered mode of outgrowth into the spinal white matter is shown in Fig. 1. After a waiting period (Donatelle 1977; Gribnau et al. 1986), the axons exit from the vDF by collateral branching in a rostro-caudal wave along the spinal cord (Kuang and Kalil 1991). Initially, these collaterals branch extensively in the gray matter, especially in the cervical and lumbar enlargements (Karimi-Abdolrezaee et al. 2002) where they finally transmit signals to muscles that control fore- and hindlimbs, respectively. This process of extensive collateral branching and arborization in the spinal gray is finally refined based on the connections made and mediated by the activity-dependent remodeling of the synaptic connections between the CST fibers and target interneurons (Ohno and Sakurai 2005). The interneurons have already then made contacts with the motoneurons in the ventral gray matter and the latter already have functional connections with the flexor and extensor muscles in fore- and hindlimbs. In view of functionality and the acquisition of voluntary movements, as this is the main function of the CST, it should be noted that learning the full complexity of locomotion is only possible if the CST is innervating not only the cervical but also the lumbar spinal cord. Then, finally, when the CST is fully grown, at the end of the third postnatal week, although myelination of fibers in the vDF may still take place (Gorgels 1990; Leenen et al.1989), the animals are able to execute very precise movements of the different muscle groups in particular in the forelimbs. This is therefore why the grasping test, which depends on the fine movements and interaction between forelimb digits, is considered a behavioral outcome of functionality of the CST in rats (Stackhouse et al. 2008).Fig. 1

Bottom Line: These advances are evaluated in this review with special emphasis on the regeneration of the corticospinal tract.The corticospinal tract is often considered the ultimate challenge in demonstrating whether a repair strategy has been successful in the regeneration of the injured mammalian spinal cord.The extensive know-how of factors and cells involved in the development of the corticospinal tract, and the advances made in material science and tissue engineering technology, have provided the foundations for the optimization of the biomatrices needed for repair.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Pain Management and Research Center, Maastricht University Medical Hospital, Maastricht, The Netherlands. b.joosten@maastrichtuniversity.nl

ABSTRACT
Important advances in the development of smart biodegradable implants for axonal regeneration after spinal cord injury have recently been reported. These advances are evaluated in this review with special emphasis on the regeneration of the corticospinal tract. The corticospinal tract is often considered the ultimate challenge in demonstrating whether a repair strategy has been successful in the regeneration of the injured mammalian spinal cord. The extensive know-how of factors and cells involved in the development of the corticospinal tract, and the advances made in material science and tissue engineering technology, have provided the foundations for the optimization of the biomatrices needed for repair. Based on the findings summarized in this review, the future development of smart biodegradable bridges for CST regrowth and regeneration in the injured spinal cord is discussed.

Show MeSH
Related in: MedlinePlus