Kwangmin Park

Jae Won Ahn, Kwangmin Park, Eun Hye Lee, Eun Ju Lee, Haneul Lee, Ah Yeoung Kim, Minju Jung, Hyunwoo Jin, Jae-Kyun Kim, Jaewon Lim, Sunghyun Kim, and Jungho Kim. Biomed Sci Letters 2026;32:273-84. https://doi.org/10.15616/BSL.2026.32.3.273

Extracellular vesicles (EVs), particularly small EVs or exosomes, are promising cell-free therapeutics with superior biocompatibility and intrinsic targeting for synthetic nanoparticles. However, conventional bulk preparation methods suffer from low yield, poor reproducibility, and structural instability. Microfluidic technologies resolve these issues by enabling precise, automated, and low-shear fluidic manipulation. This mini-review highlights recent advances in microfluidic-engineered exosomes for cancer immunotherapy and infectious diseases. We evaluate critical microfluidic strategies for isolation, surface engineering, and cargo loading, contrasting platforms like ExoArc, acoustofluidics, cellular nanoporation, and electroporation. Particular emphasis is placed on complex modalities, including immune cell-derived exosomes (IEX), neo-antigen presentation, chimeric antigen receptor (CAR)-derived exosomes, and targeted siRNA delivery networks. Crucially, we analyze the technological disconnect between analytical microfluidic scales and massive therapeutic manufacturing volumes, addressing how physical forces risk damaging conformationally sensitive surface proteins (e.g., CAR scFv). Finally, we outline future perspectives, including high-throughput 3D-multiplexed networks, stimulus-responsive scarless elution, and integrated “sample-to-therapy” circuits. Guided by the MISEV2023 guidelines, this review frames the path toward standardized, clinical-scale engineering of multi-functional, cell-free immunotherapies.

Dong Geon Lee, Yujin Park, Kwangmin Park, Ah Yeoung Kim, Heeju Nam, Hyunwoo Jin, Sunghyun Kim, and Jungho Kim. Biomed Sci Letters 2026;32:61-72. https://doi.org/10.15616/BSL.2026.32.1.61

Post-mortem interval (PMI) analysis plays a crucial role in forensic investigations, providing essential insights into the time since death. This study examined histological changes and ribonucleic acid (RNA) quantification across major organs to identify molecular indicators for PMI estimation. Because RNA gradually degrades after death, understanding its stability under different tissue, temperature, and PMI conditions provides valuable forensic insights. We analyzed post-mortem changes in total RNA from the heart, kidney, liver, and lung tissues of Sprague Dawley rats stored at 4 °C and 26 °C. Tissue samples were collected at various PMIs and evaluated histologically for cellular integrity. Total RNA concentration and purity were measured, and complementary DNA (cDNA) was synthesized for molecular analysis. Expression levels of 5S rRNA, B2m, Gapdh, and Sort1 were quantified using reverse transcription quantitative PCR (RT-qPCR). The results showed that PMI and organ type significantly affected total RNA concentration, whereas temperature exerted only a minor effect. Among the four target genes, 5S rRNA exhibited the lowest Ct values, indicating the highest stability. Notably, RNA degradation patterns varied with temperature, particularly in kidney and liver tissues. These findings suggest that RNA-based molecular markers, particularly 5S rRNA, may serve as promising indicators for accurate PMI estimation.

The postmortem interval (PMI), defined as the time elapsed between death and the discovery or examination of the body, is a crucial parameter in forensic science for estimating the time of death. There are many ways to measure the PMI, such as Henssge’s nomogram, which uses rectal temperature measurement; livor mortis; rigor mortis; and forensic entomology. However, these methods are usually affected by various conditions in the surrounding environment. The purpose of the present study was to compare molecular genetics and histological changes in the brain and skeletal muscle tissues of SD rats over increasing periods of time after death. For the PMIs, we considered 0 h, 6 h, 12 h, 24 h, 36 h, 48 h, 4 days, 6 days, 8 days, 10 days, 14 days, and 21 days and compared them at 4 °C and 26 °C. Hematoxylin and Eosin (H&E) staining was performed to observe tissue changes. Morphological tissue changes were observed in cells for up to 21 days at 4 °C, and cell destruction was visually confirmed after 14 days at 26 °C. Total RNA (tRNA) was isolated from each tissue sample, and complementary DNA (cDNA) was synthesized. A reverse transcription quantitative PCR (RT-qPCR) SYBR Green assay targeting three types of housekeeping genes, including Gapdh, Sort1, B2m, and 5S rRNA, was performed. The results showed that Gapdh and 5S rRNA were highly stable and could be better RNA targets for estimating the PMI in brain and skeletal muscle tissues. Conversely, Sort1 and B2m showed poor stability and low expression levels. In conclusion, these molecular biomarkers could be used as auxiliary indicators of the PMI in human, depending on the stability of the marker.

Ji-Hoi Kim, Soonmog So, Kwangmin Park, Dong Hyeok Kim, Baek-Hui Kim, Hyunwoo Jin, and Kyung Eun Lee. BSL 2025;31:187-96. https://doi.org/10.15616/BSL.2025.31.2.187

Kwangmin Park, Ji Hoi Kim, Dong Hyeok Kim, Jungho Kim, Hyunwoo Jin, and Kyung Eun Lee. BSL 2025;31:59-69. https://doi.org/10.15616/BSL.2025.31.1.59

Background: When a body is discovered at a crime or murder scene, it is crucial to examine the body and estimate its postmortem interval (PMI). Accurate estimation of PMI is vital for identifying suspects and providing clues to resolve the case. MicroRNAs (miRNAs or miRs) are small non-coding RNAs that remain relatively stable in the cell nucleus even after death-related changes occur. Objective: This study developed a molecular beacon probe for mmu-miR-133a-5p and assessed its use in mouse muscle tissue at temperatures of 4 °C and 21 °C to estimate the PMI. Methods: A total of 36 healthy adult male BALB/c mice were divided into 9 PMI time points (0, 2, 6, 8, and 10 days) with 3 mice per time point, and they were exposed to 4 °C and 21 °C. Next, the expression pattern of mmu-miR-133a in the skeletal muscle tissue over a 10-day PMI period was analyzed using the developed molecular beacon probe. Results: The molecular beacon (MB) probe was designed for optimal thermodynamic stability with a hairpin structure that opened in the presence of mmu-miR-133a-5p, thus separating the fluorophore from the quencher and resulting in a strong fluorescence signal at 495 nm. Fluorescence intensity increased with mmu-miR-133a-5p concentration from 1 ng/μL to 1000 ng/μL and exhibited a strong correlation (R² = 0.9966) and a detection limit of 1 ng/μL. Subsequently, the expression level of mmu-miR-133a-5p was observed to be stable in mouse skeletal muscle tissue at both 4 °C and 21 °C. Conclusions: This user-friendly assay can complete measurements in just 30 min after RNA extraction and is suitable for point-of-care testing, and it possesses the potential to improve existing complex and time-consuming methods for PMI estimation.

Backgroud Accurate estimation of post-mortem interval (PMI) is crucial in forensic investigations. MicroRNAs (miRNAs or miRs) are small non-coding RNAs that remain relatively stable within the cell nucleus despite post-mortem changes. Objective We assessed three target genes (miR-122, miR-133a, and miR-206) for PMI estimation using 72 healthy adult male BALB/c mice exposed to two different temperatures (4 and 21℃) at nine different time points over 10 days. Methods Initially, the stability of the two reference genes (RNU6B and 5 srRNA) was evaluated using gene stability analysis tools (Delta Ct, Best Keeper, and Genorm) to select the optimal reference gene. RNU6B was found to be the most stable endogenous control. Subsequently, the expression patterns of miR-122, miR-133a, and miR-206 were analyzed within a 10-day PMI period using the heart, skeletal muscle, liver, and brain tissues. Results At 4℃, miR-122 levels significantly decreased on days 8 and 10 in all tissues, with only the liver showing significant changes at 21℃. MiR-133a decreased over time in the heart, muscles, and brain, showing a dramatic decrease on days 8 and 10 in the heart and muscles at both temperatures. Although miR-206 levels decreased over time in muscles and liver at 4 ℃, these increased in the brain at 21 ℃, with no expression changes in other organs. Conclusion In summary, miR-122, miR-133a, and miR-206 are potential PMI markers in heart and skeletal muscle tissues.