Development of bioactive constructs through cell crosslinking for tissue regeneration

Injectable systems are particularly attractive for a minimally invasive
approach in tissue engineering applications. Many different methods
for in situ crosslinking have been investigated however the ability of
cells to promote hydrogel formation has not been fully explored. This
study addressed the hypothesis that cells can promote crosslinking of
chitosan microparticles forming a tridimensional network. Through
covalent immobilization we were able to functionalize particles with
specific antibodies, used to promote the attachment of cells and growth
factors of interest. CD90 anti-human antibodies that are highly
expressed by human adipose stem cells (hASCs) were successfully conjugated
with chitosan microparticles. A tridimensional hydrogel was
obtained by the assembly of the modified chitosan microparticles with
hASCs and was stabilized by the crosslinks established by the
entrapped cells. The degree of crosslinking of the structure could be
regulated by the cell concentration in each construct. Moreover we
believe that a combination of microparticles tailored with specific
growth factors will increase the stability of the construct and promote
cell differentiation. It is well established that platelets are an important
source of autologous growth factors that can modulate cell growth and
differentiation. In this study we propose antibody-conjugated particles
as a method to select specific growth factors from the mixture
obtained from platelet lysates. The obtained construct simultaneously
provides support for stem cell growth as well localized and sustained
presentation of factors to modulate cell differentiation. We intend to
design a novel multifunctional injectable system that may be customized
by combining particles with different growth factors for a specific
application.Injectable systems are particularly attractive for a minimally invasive
approach in tissue engineering applications. Many different methods
for in situ crosslinking have been investigated however the ability of
cells to promote hydrogel formation has not been fully explored. This
study addressed the hypothesis that cells can promote crosslinking of
chitosan microparticles forming a tridimensional network. Through
covalent immobilization we were able to functionalize particles with
specific antibodies, used to promote the attachment of cells and growth
factors of interest. CD90 anti-human antibodies that are highly
expressed by human adipose stem cells (hASCs) were successfully conjugated
with chitosan microparticles. A tridimensional hydrogel was
obtained by the assembly of the modified chitosan microparticles with
hASCs and was stabilized by the crosslinks established by the
entrapped cells. The degree of crosslinking of the structure could be
regulated by the cell concentration in each construct. Moreover we
believe that a combination of microparticles tailored with specific
growth factors will increase the stability of the construct and promote
cell differentiation. It is well established that platelets are an important
source of autologous growth factors that can modulate cell growth and
differentiation. In this study we propose antibody-conjugated particles
as a method to select specific growth factors from the mixture
obtained from platelet lysates. The obtained construct simultaneously
provides support for stem cell growth as well localized and sustained
presentation of factors to modulate cell differentiation. We intend to
design a novel multifunctional injectable system that may be customized
by combining particles with different growth factors for a specific
application