In Vivo Micro‐Computerized Tomography Tracking of Human Periodontal Ligament Stem Cells Labeled with Gold Nanocomplexes

Abstract

Gold nanocomplexes have been proposed as contrast agents for computerized tomography (CT) and cell tracking, which is especially useful in stem cell therapy. However, their potential for long-term in vivo cell detection is still unknown. This study proposes an optimized approach to labeling human periodontal ligament stem cells (hPDLSCs) with gold nanocomplexes to evaluate their detection with micro-CT after transplantation at four different rat tissues. The gold nanocomplexes of 0.05 mg mL −1 do not affect cell viability nor osteogenic differentiation capacity, but render fluorescent and radiopaque hPDLSCs. Excellent linear correlation with the number of labeled cells is shown over a wide range (r = 0.99, P < 0.01), with a detection limit of ≈1.2 × 10 3 cells/μL. In vivo, strong, and durable detection of transplanted labeled cells within 5 days at all investigated areas is seen by micro-CT and immunohistochemical assay. This approach confirms the potential of gold nanocomplexes in longitudinal in vivo cell tracking, which may facilitate their application in CT image-guided interventions commonly used in oromaxillofacial or systemic applications of stem cell therapy.

Computed tomography lacks sensitivity to image gold labelled mesenchymal stromal cells in vivo as evidenced by multispectral optoacoustic tomography

“…Cell labelling strategies to achieve this vary widely (table 1). Studies describe using gold nanoparticles with different surface chemistries, diameters, initial gold concentrations, and incubation times (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36). It has been shown that the properties of gold nanoparticles impact cell uptake (25), which agrees with the variation in uptake efficiency reported in these studies.…”

“…This reflects the complexity of comparing results in the field of gold-labelled cell tracking by CT. Nonetheless, at least twelve reports suggest that CT enables longitudinal tracking of gold-labelled cells (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36), although it should be noted that at least 6 of these originate from the same research group. In contrast, despite BLI and MSOT confirming the presence of cells in the mice, our study failed to detect contrast generated by the gold-labelled MSCs by CT regardless of whether they were delivered SC or IV.…”

Biomimetic Periodontal Ligament Transplantation Activated by Gold Nanoparticles Protects Alveolar Bone

“…AuNCs (AuNP‐poly‐ l ‐lysine hydrobromide‐rhodamine B isothiocyanate) were freshly prepared as previously described. [ 23 ] Afterward, their spherical morphology, particle diameter, size distribution, zeta potential, and surface features were characterized by high‐resolution transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), and electrophoretic light scattering (ELS), respectively.…”

“…This contradicts prior research using AuNCs at 0.05 mg L −1 where only ALP was selected as the osteogenic marker. [ 23 ] In the present study, the selection of multiple osteogenic markers (ALP, COL1, OSTERIX, and RUNX2) and the extended observation period (14 and 21 d) allowed for a more comprehensive evaluation of osteogenic differentiation.…”

“…All cells were routinely screened in the lab for the expression of the following markers: CD29, CD31 (negative), CD34 (negative), CD44, CD45 (negative), CD73, CD90, CD105, as described previously. [ 23 ] Their MSC properties were investigated by the following experiments: Colony‐forming unit assay: hPDLSCs of 4 × 10 3 per well were inoculated in six‐well plates with 2 mL culture medium changed every 2 d. After 3 weeks, the cells were fixed with 4% PFA for 20 min and stained with 1% crystal violet for 1 h. The cell colonies consisting of more than 50 cells were observed using light microscopy (Primo Vert, Carl Zeiss, Jena, Germany). Cell‐doubling time assay: hPDLSCs of 5 × 10 5 per well were inoculated in T175 culture flasks with 20 mL culture medium changed every 2 d. After 3, 6, 9, and 12 d, the cells were collected and counted to produce a cell‐growth curve. Cell viability assay: hPDLSCs of 5 × 10 3 per well were inoculated in 96‐well plates with 0.1 mL culture medium changed every 2 d. After 1, 3, 5, and 7 d, the cell viability was longitudinally assessed by AlamarBlue HS Cell Viability Reagent as described before. [ 56 ] Osteogenic differentiation assay: hPDLSCs of 8 × 10 3 per well were inoculated in 24‐well plates with 0.5 mL culture medium.…”