In order to analyze and study the relationship between the sampling location, degree of damage, and preparation quality of placental hematopoietic stem cells, it is necessary to optimize the precise sampling location of placental samples, establish criteria for examination grading, and provide guidance and a foundation for clinical collection of placental samples and establishment of a high-quality placental hematopoietic stem cell sample bank.

After sampling the placental hematopoietic stem cell preparation site, STR detection was performed to analyze the mosaicism of maternal blood at different sampling sites and determine the precise location of sampling. Simultaneously, quality tests including grading the degree of placental damage, total nucleated cell number (TNC), CD34⁺CD45^dim flow rate, and granulocyte- macrophage colony-forming unit (CFU-GM) were conducted on samples with varying levels of damage to analyze the quality indicators of placenta samples with different degrees of damage. Independent sample t-tests or non-parametric tests were utilized for data comparison and analysis.

Analysis of STR test results, peripheral blood cell chimerism [ (39.57 ± 4.56) % vs (22.37 ± 3.61) %] was elevated at sampling site 2 compared to sampling site 1, while the peripheral blood cell chimerism rate at sampling point 3 [ (22.37 ± 3.61) % versus (2.17 ± 0.17) %] decreased. The difference was statistically significant (P < 0.01). Peripheral blood cell chimerism was elevated at sampling sites 1 and 2 compared with sampling site 3. Compared with the unbroken group, the mean number of TNCs was lower in the tertiary broken group [ (5.52 ± 0.35) × 10⁸ compared with (6.92 ± 0.83) × 10⁸], and the difference was statistically significant (P < 0.01). Compared with the unbroken group, the proportion of CD34⁺CD45^dim cells to TNCs was elevated in the primary broken group and decreased in the secondary and tertiary broken group, with no statistically significant difference.Compared with the undamaged group, the average total number of CFU-GM in the second and third level damaged groups decreased, and the difference was statistically significant.

The mosaicism rate of maternal blood varies significantly across different sampling sites, highlighting the importance of sampling as close to the fetal surface as possible in order to obtain high-quality placental hematopoietic stem cells. Additionally, the grading of placenta samples revealed a negative correlation between the degree of damage and the number of TNC, CD34⁺CD45^dim flow cells, CFU- GM colonies, and effective hematopoietic stem cells. This suggests that complete collection of placental tissue is crucial.