Structure and mechanics of native and decellularized porcine cranial dura mater

The dura mater is the outermost layer of meninges and consists of a dense elastic membrane that keeps cere-brospinal fluid inside the cavity.In most cranial surgical interventions,the dura mater is incised and needs to be repaired with a graft replacement.We assessed decellularized porcine dura mater as a novel graft material by quantifying the mechanical and structural properties of the dura membrane.Porcine dura mater was decellular-ized using the Sodium Dodecyl Sulfate(SDS)technique and subjected to uniaxial tensile testing,micro indentation testing,histological analysis,and Transmission Electron Microscopy(TEM).For native dura,we found the tensile modulus in the linear region(15%-25%strain)to be 19.31±1.23 MPa,with an initial tensile modulus(0%-3.5%strain range)of 451±0.30 kPa,and the failure stress as 4.61±1.50 MPa at 35%strain.For decellularized dura,the tensile modulus in the linear region was 10.81±0.88 MPa,the initial tensile modulus was 226±22 kPa,and the failure stress was 4.55±1.05 MPa at 55%strain.The effective compressive modulus was 7 to 19 kPa and 19-57 kPa for the native dura and the decellularized dura,respectively.Our histological and TEM observations showed that the orientation of fibers within the dura was maintained after decellularization.In short,our study demonstrated that decellularized porcine dura was able to maintain its overall morphological/structural integrity and preserve the native dura’s mechanical behavior,which provides a solid foundation for its use as a functional grafting material.

Structural and biomechanical characterizations of acellular porcine mitral valve scaffolds:anterior leaflets,posterior leaflets,and chordae tendineae

Mitral valve(MV)tissue engineering is still in its early stage,and one major challenge in MV tissue engineering is to identify appropriate scaffold materials.With the potential of acellular MV scaffolds being demonstrated recently,it is important to have a full understanding of the biomechanics of the native MV components and their acellular scaffolds.In this study,we have successfully characterized the structural and mechanical properties of porcine MV components,including anterior leaflet(AL),posterior leaflet(PL),strut chordae,and basal chordae,before and after decellularization.Quantitative DNA assay showed more than 90%reduction in DNA content,and Griffonia simplicifolia(GS)lectin immunohistochemistry confirmed the complete lack of porcine𝛼-Gal antigen in the acellular MV components.In the acellular AL and PL,the atrialis,spongiosa,and fibrosa trilayered structure,along with its ECM constitutes,i.e.,collagen fibers,elastin fibers,and portion of GAGs,were preserved.Never-theless,the ECM of both AL and PL experienced a certain degree of disruption,exhibiting a less dense,porous ECM morphology.The overall anatomical morphology of the strut and basal chordae were also maintained af-ter decellularization,with longitudinal morphology experiencing minimum disruption,but the cross-sectional morphology exhibiting evenly-distributed porous structure.In the acellular AL and PL,the nonlinear anisotropic biaxial mechanical behavior was overall preserved;however,uniaxial tensile tests showed that the removal of cellular content and the disruption of structural ECM did result in small decreases in maximum tensile modulus,tissue extensibility,failure stress,and failure strain for both MV leaflets and chordae.