Directing the organization of cells into a tissue with defined architectures is one use of biomaterials for regenerative medicine. To this end, hydrogels are widely investigated as they have mechanical properties similar to native soft tissues and can be formed in situ to conform to a defect. Herein, we describe the development of porous hydrogel tubes fabricated through a two-step polymerization process with an intermediate microsphere phase that provides macroscale porosity (66.5%) for cell infiltration. These tubes were investigated in a spinal cord injury model, with the tubes assembled to conform to the injury and to provide an orientation that guides axons through the injury. Implanted tubes had good apposition and were integrated with the host tissue due to cell infiltration, with a transient increase in immune cell infiltration at 1 week that resolved by 2 weeks post injury compared to a gelfoam control. The glial scar was significantly reduced relative to control, which enabled robust axon growth along the inner and outer surface of the tubes. Axon density within the hydrogel tubes (1744 axons/mm2) was significantly increased more than 3-fold compared to the control (456 axons/mm2), with approximately 30% of axons within the tube myelinated. Furthermore, implantation of hydrogel tubes enhanced functional recovery relative to control. This modular assembly of porous tubes to fill a defect and directionally orient tissue growth could be extended beyond spinal cord injury to other tissues, such as vascular or musculoskeletal tissue. STATEMENT OF SIGNIFICANCE: Tissue engineering approaches that mimic the native architecture of healthy tissue are needed following injury. Traditionally, pre-molded scaffolds have been implemented but require a priori knowledge of wound geometries. Conversely, hydrogels can conform to any injury, but do not guide bi-directional regeneration. In this work, we investigate the feasibility of a system of modular hydrogel tubes to promote bi-directional regeneration after spinal cord injury. This system allows for tubes to be cut to size during surgery and implanted one-by-one to fill any injury, while providing bi-directional guidance. Moreover, this system of tubes can be broadly applied to tissue engineering approaches that require a modular guidance system, such as repair to vascular or musculoskeletal tissues.

• Klíčová slova
• Axon elongation, Modular biomaterial, Spinal cord injury, Tissue repair,
• MeSH
• axony účinky léků   patologie   MeSH
• hydrogely farmakologie   MeSH
• jizva patologie   MeSH
• lokomoce účinky léků   MeSH
• maleimidy chemie   MeSH
• mikrosféry MeSH
• myelinová pochva účinky léků   metabolismus   MeSH
• myši inbrední C57BL MeSH
• neuroglie patologie   MeSH
• polyethylenglykoly chemie   MeSH
• polymerizace MeSH
• poranění míchy patologie   patofyziologie   MeSH
• poréznost MeSH
• reagencia zkříženě vázaná chemie   MeSH
• regenerace nervu účinky léků   MeSH
• tkáňové podpůrné struktury chemie   MeSH
• zadní končetina účinky léků   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• hydrogely MeSH
• maleimide MeSH Prohlížeč
• maleimidy MeSH
• polyethylenglykoly MeSH
• reagencia zkříženě vázaná MeSH

Methacrylate hydrogels have been extensively used as bridging scaffolds in experimental spinal cord injury (SCI) research. As synthetic materials, they can be modified, which leads to improved bridging of the lesion. Fibronectin, a glycoprotein of the extracellular matrix produced by reactive astrocytes after SCI, is known to promote cell adhesion. We implanted 3 methacrylate hydrogels: a scaffold based on hydroxypropylmethacrylamid (HPMA), 2-hydroxyethylmethacrylate (HEMA) and a HEMA hydrogel with an attached fibronectin (HEMA-Fn) in an experimental model of acute SCI in rats. The animals underwent functional evaluation once a week and the spinal cords were histologically assessed 3 months after hydrogel implantation. We found that both the HPMA and the HEMA-Fn hydrogel scaffolds lead to partial sensory improvement compared to control animals and animals treated with plain HEMA scaffold. The HPMA scaffold showed an increased connective tissue infiltration compared to plain HEMA hydrogels. There was a tendency towards connective tissue infiltration and higher blood vessel ingrowth in the HEMA-Fn scaffold. HPMA hydrogels showed a significantly increased axonal ingrowth compared to HEMA-Fn and plain HEMA; while there were some neurofilaments in the peripheral as well as the central region of the HEMA-Fn scaffold, no neurofilaments were found in plain HEMA hydrogels. In conclusion, HPMA hydrogel as well as the HEMA-Fn scaffold showed better bridging qualities compared to the plain HEMA hydrogel, which resulted in very limited partial sensory improvement.

• Klíčová slova
• connective tissue, hydrogel, locomotor test, neurofilaments, plantar test, spinal cord injury,
• MeSH
• axony fyziologie   MeSH
• biokompatibilní materiály MeSH
• biologické markery MeSH
• exprese genu MeSH
• extracelulární matrix metabolismus   MeSH
• fyziologická neovaskularizace MeSH
• hematoencefalická bariéra metabolismus   MeSH
• hojení ran MeSH
• hydrogely * MeSH
• krysa rodu Rattus MeSH
• methakryláty * chemie   MeSH
• modely nemocí na zvířatech MeSH
• pojivová tkáň MeSH
• poranění míchy etiologie   metabolismus   patologie   terapie   MeSH
• regenerace nervu * MeSH
• tkáňové podpůrné struktury MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biokompatibilní materiály MeSH
• biologické markery MeSH
• hydrogely * MeSH
• methakryláty * MeSH

While many types of biomaterials have been evaluated in experimental spinal cord injury (SCI) research, little is known about the time-related dynamics of the tissue infiltration of these scaffolds. We analyzed the ingrowth of connective tissue, axons and blood vessels inside the superporous poly (2-hydroxyethyl methacrylate) hydrogel with oriented pores. The hydrogels, either plain or seeded with mesenchymal stem cells (MSCs), were implanted in spinal cord transection at the level of Th8. The animals were sacrificed at days 2, 7, 14, 28, 49 and 6 months after SCI and histologically evaluated. We found that within the first week, the hydrogels were already infiltrated with connective tissue and blood vessels, which remained stable for the next 6 weeks. Axons slowly and gradually infiltrated the hydrogel within the first month, after which the numbers became stable. Six months after SCI we observed rare axons crossing the hydrogel bridge and infiltrating the caudal stump. There was no difference in the tissue infiltration between the plain hydrogels and those seeded with MSCs. We conclude that while connective tissue and blood vessels quickly infiltrate the scaffold within the first week, axons show a rather gradual infiltration over the first month, and this is not facilitated by the presence of MSCs inside the hydrogel pores. Further research which is focused on the permissive micro-environment of the hydrogel scaffold is needed, to promote continuous and long-lasting tissue regeneration across the spinal cord lesion.

• MeSH
• axony patologie   MeSH
• biokompatibilní materiály chemie   MeSH
• časové faktory MeSH
• fyziologická neovaskularizace MeSH
• hydrogely MeSH
• krysa rodu Rattus MeSH
• oligopeptidy chemie   MeSH
• polyhydroxyethylmethakrylát chemie   MeSH
• poranění míchy patologie   patofyziologie   terapie   MeSH
• poréznost MeSH
• potkani Wistar MeSH
• regenerace míchy fyziologie   MeSH
• testování materiálů MeSH
• tkáňové podpůrné struktury chemie   MeSH
• transplantace mezenchymálních kmenových buněk * MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• Názvy látek
• biokompatibilní materiály MeSH
• hydrogely MeSH
• oligopeptidy MeSH
• polyhydroxyethylmethakrylát MeSH
• seryl-isoleucyl-lysyl-valyl-alanyl-valinamide MeSH Prohlížeč

Spinal cord injury (SCI) results in neural loss and consequently motor and sensory impairment below the injury. There are currently no effective therapies for the treatment of traumatic SCI in humans. Various animal models have been developed to mimic human SCI. Widely used animal models of SCI are complete or partial transection or experimental contusion and compression, with both bearing controversy as to which one more appropriately reproduces the human SCI functional consequences. Here we present in details the widely used procedure of complete spinal cord transection as a faithful animal model to investigate neural and functional repair of the damaged tissue by exogenous human transplanted cells. This injury model offers the advantage of complete damage to a spinal cord at a defined place and time, is relatively simple to standardize and is highly reproducible.

• MeSH
• embryonální kmenové buňky MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• modely nemocí na zvířatech * MeSH
• poranění míchy patologie   patofyziologie   terapie   MeSH
• translační biomedicínský výzkum * MeSH
• transplantace buněk * MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH