Synthesis and functionalization of superparamagnetic poly- ɛ -caprolactone microparticles for the selective isolation of subpopulations of human adipose-derived stem cells

Abstract

There has been a growing interest in using biofunctionalized magnetic particles for cell isolation. This paper describes the synthesis and characterization of magnetite-polymer (Fe 3 O 4 -poly-1-caprolactone, magnetite-PCL) microparticles surface functionalized with amino and epoxy groups allowing easy covalent attachment of specific antibodies and subsequent ability to bind target cells. Particles with different sizes (4 -135 mm), spherical shape and superparamagnetic behaviour (magnetite content of about 13 wt%) were obtained. The functionalized microparticles presented high protein-binding capacity (coupling efficiency of 47% for epoxy-and 71% for amino-functionalized particles) with a low level of non-specific binding. We have further investigated the influence of initial protein concentration, pH, ionic strength, temperature and incubation time on the capacity of amino-functionalized particles to bind protein molecules. The results showed that maximum protein coupling is rapidly achieved ( 5 h) at pH 5.5 and low ionic strength (0.05 M NaCl). Furthermore, when cultured in direct contact with osteoblast-like cells (Saos-2) or human-derived adipose stem cells (ASCs), the amino-functionalized particles did not affect the proliferation and morphology of the cells. As a proof of principle for the application of magnetic microparticles for cell isolation, CD105 (endoglin) antibody was coupled to the magnetic particle surface to bind subpopulations of human ASCs expressing the CD105 antigen. The isolation of CD105þ ASCs from a heterogeneous cell population was confirmed by flow cytometry analysis. Given the demonstrated potential of functionalized magnetite-PCL microparticles for selective cell isolation, we expect that these particles may be further applied in immuno-magnetic cell separation owing to their versatility and ease of surface modification.

Liposomes in tissue engineering and regenerative medicine

“…Tissue regeneration depends not only on the bioactive agent itself such as growth factors (GFs), but also on the various parameters associated with its presentation, including concentration, spatio-temporal gradients, combination with other GFs and the target cell type [151][152][153][154]. Bioactive agent-loaded liposomes combined with scaffolds offer various intrinsic benefits such as: (i) effective concentration; (ii) stable concentration gradients; (iii) multiple bioactive agent delivery; and (iv) spatial patterning [27].…”

Selective Cell Recruitment and Spatially Controlled Cell Attachment on Instructive Chitosan Surfaces Functionalized with Antibodies

“…The most common and effective method currently reported for isolation of a specific cell type involves the use of magnetic beads coated with antibodies for target cells. This technique requires the attachment of magnetic beads to the cells that may be undesirable for cell-based therapeutic applications [15,16].…”

“…Compared with currently available devices found in literature the system herein proposed besides effective it is relatively low cost using a biomaterial with easy chemistry that can be later implantable [10][11][12][13][14][15][16]. The method proposed in this work allows the isolation of a target cell type from a mixed cell population with relatively high purity, decreasing cell handling where recruited cells can be used straightaway.…”

“…The most common method for cell sorting and enrichment is based on magnetic cell separation. Magnetic beads utilize a capturing surface or matrix coated with an antibody that has high affinity for a specific cell-surface marker binding target cells [15,16]. To date, few studies reported the use of a biomaterial surfaces functionalized with antibodies for cell capture.…”

Modeling the efficiency of a magnetic needle for collecting magnetic cells

“…The targeted cells can then be collected by removing the fluid and nonmagnetic sample components, while the selected cells are held to the wall of the tube by the magnet. This simple separation method has been applied to both synthesized magnetic particles (Stuckey et al 2006, Balmayor et al 2011) and naturally occurring particles made from labeling magnetobacteria (Kuhara et al 2004, Matsunaga et al 2006 , Yoshino et al 2008, Kuhara et al 2009) and to a wide variety of cell types including adipose and hematopoietic stem cells (Balmayor et al 2011, Kuhara et al 2009), mononuclear cells (Kuhara et al 2004), dendritic cells (Matsunaga et al 2006) and transplanted cells (Stuckey et al 2006). …”