LDSCs are hypothesised to be a subset of MSCs and these two cell populations share many stem cell characteristics, however there are also important differences.
The Effects of Ageing and Injury on LDSCs. Ageing and injury/degeneration have both been shown to have an effect on the function and phenotype of various stem cell types, including MSCs [30, 31], TDSCs [32-34], and LDSCs isolated from periodontal ligament [35, 36].
In LDSCs derived from human ACL, age has been shown to cause a decrease in the rate of proliferation as well as reduced osteogenesis .
An Alternative Source of LDSCs. The cells isolated in the aforementioned studies have all been negative for haematopoietic and endothelial markers; however, one group has identified a cell population within the ACL which is positive for CD34 [37, 39], suggesting an alternative vascular source for stem cells located within the ACL.
Recent studies have investigated the use of PDLSCs in tissue engineering approaches in dentistry for the repair of periodontal cementum/bone and ligament with successful outcomes [12, 13, 45]; however, little research has been conducted in to the use of LDSCs for other forms of ligament repair.
This study highlights the potential use of LDSCs for repair of ligament injuries outside the field of dentistry.
As previously discussed, LDSCs positive for CD34 have also been isolated from ACL tissue and one study has used these cells to investigate the effects of angiogenesis on ACL repair strategies .
As previously discussed, one group have found CD34+ stem cells within human ACL tissue which possess all the properties found in other LDSCs .
Although the number of studies investigating LDSCs of nondental origin is increasing, particularly in recent years, there is still very little information on many aspects of these cells.