Developing tools to reproduce and manipulate the cell micro-environment, 
including the location and shape of cell patterns, is essential for tissue 
engineering. Parallel to inkjet printing and pressure-operated mechanical 
extruders, laser-assisted bioprinting (LAB) has emerged as an alternative 
technology to fabricate two- and three-dimensional tissue engineering products. 
The objective of this work was to determine laser printing parameters for 
patterning and assembling nano-hydroxyapatite (nHA) and human osteoprogenitors 
(HOPs) in two and three dimensions with LAB. The LAB workstation used in this 
study comprised an infrared laser focused on a quartz ribbon that was coated 
with a thin absorbing layer of titanium and a layer of bioink. The scanning 
system, quartz ribbon and substrate were piloted by dedicated software, allowing 
the sequential printing of different biological materials into two and/or three 
dimensions. nHA printing material (bioink) was synthesized by chemical 
precipitation and was characterized prior and following printing using 
transmission electron microscopy, Fourier transformed infrared spectroscopy and 
x-ray diffraction. HOP bioink was prepared using a 30 million cells ml(-1) 
suspension in culture medium and cells were characterized after printing using a 
Live/Dead assay and osteoblastic phenotype markers (alcaline phosphatase and 
osteocalcin). The results revealed that LAB allows printing and organizing nHA 
and HOPs in two and three dimensions. LAB did not alter the physico-chemical 
properties of nHA, nor the viability, proliferation and phenotype of HOPs over 
time (up to 15 days). This study has demonstrated that LAB is a relevant method 
for patterning nHA and osteoblastic cells in 2D, and is also adapted to the 
bio-fabrication of 3D composite materials.