LPA

LPA is contained in some skin moisturizers so it might be available for sale.  One study found that LPA was not able to induce chondrocyte growth. LPA did not upregulate Sox9 in mesenchymal stem cells in one study.

Stimulatory actions of lysophosphatidic acid on mouse ATDC5 chondroprogenitor cells.

"Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are bioactive lysophospholipids that affect various cellular processes through G protein-coupled receptors. E11.5 mouse embryos strongly expressed the LPA receptor subtype LPA(1) in cartilaginous bone primordia and the surrounding mesenchymal cells. The mouse clonal cell line ATDC5 undergoes a sequential differentiation of chondroprogenitor cells in vitro. Undifferentiated and differentiated ATDC5 cells express LPA(1) and other lysophospholipid receptors including S1P receptor S1P(1) and S1P(2). LPA markedly stimulates both DNA synthesis and the migration of ATDC5 chondroprogenitor cells in culture, whereas S1P suppresses the migration of these cells. Treatment with Ki16425, an LPA(1)- and LPA(3)-specific receptor antagonist, suppressed the fetal bovine serum-stimulated migration of ATDC5 cells by almost 80%.

"autotaxin (ATX), a tumor cell motility-stimulating factor, is abundantly expressed in the condensing mesenchyme in the epiphyseal region of the developing limb in mouse and chick embryos"

"ATX [is] a secreted lysophospholipase D and plays a principal role in LPA production in the body"

" The region of LPA 1 expression was found to be overlapped with Sox9-positive prechondrogenic region"

LPA increased ERK1/2-phosphorylation, increasing from doses 0 to 10 microM.   ERK1/2-p levels returned to normal after 10 minutes.

Lower concentrations of LPA were more stimulatory to migration than higher concentrations.  LPA also stimulates MSC migration.

An LPA receptor antagonist repressed the chondrogenic differentiation of ATDC5 cells.