The HD10.6 cell line is no longer available. It was developed by researchers at Celgene Corporation which was a biopharmaceutical company. Now Celgene has being acquired by Bristol Myers Squibb. While Celgene initially held this cell line, it appears to no longer be accessible through Celgene or other standard distributors.
The HD10.6 cell line is an immortalized human dorsal root ganglion (DRG) neuron. As an alternative you could use F11, ND7/23 or ND-C which are hybrid cell lines, generated from fusion of rat DRG neurons and mouse neuroblastoma cells, or MED17.11 which is a mouse cell line, also derived from DRG neuron.
You could also look into induced pluripotent stem cell-derived sensory neurons (iPSC-SNs) derived from human origin. iPSCs themselves are generated from human somatic cells, and iPSC-SNs are subsequently differentiated from these human iPSCs. These iPSC-SNs are available from ATCC. ATCC offers various lines of human induced pluripotent stem cells (iPSCs), which can be differentiated into sensory neurons.