BioVector? HEK293-APP695 swedish Stable Transfectant Cell Line / HEK293-APP695 swedish 人胚腎阿爾茨海默病特異性突變穩(wěn)定轉(zhuǎn)染細(xì)胞株

一 產(chǎn)品基本信息與細(xì)胞生物學(xué)背景

• 細(xì)胞名稱：HEK293-APP695 swedish（亦書寫為 HEK293-APPsw 或 HEK293/APP695swe）。

• 物種與組織來源：人類（Homo sapiens），源自人胚腎細(xì)胞（HEK293 親本細(xì)胞），經(jīng)體外分子克隆技術(shù)穩(wěn)定轉(zhuǎn)染了帶有瑞典突變（Swedish mutation）的人源 695 氨基酸型淀粉樣前體蛋白（Amyloid Precursor Protein, APP695）基因。

• 細(xì)胞系建立背景（阿爾茨海默病體外經(jīng)典模型）：

  HEK293 細(xì)胞系由于其極高且穩(wěn)定的外源蛋白表達(dá)效率、清晰的遺傳背景和易于操作的貼壁培養(yǎng)特征，是全球制藥界與神經(jīng)科學(xué)界構(gòu)建疾病細(xì)胞模型的首選。

  APP695 是 APP 蛋白在腦部和神經(jīng)系統(tǒng)中最主要、豐度最高的剪切異構(gòu)體（Isoform）。所謂的瑞典突變（Swedish mutation），是一種家族遺傳性阿爾茨海默病（FAD）的經(jīng)典基因突變類型，其突變位點(diǎn)位于 APP 蛋白的 $\beta$-分泌酶（$\beta$-secretase）剪切位點(diǎn)處，即氨基酸序列中的 K670N / M671L（Lys670Asn / Met671Leu） 發(fā)生雙堿基替換。該突變的發(fā)生，導(dǎo)致 $\beta$-分泌酶對(duì) APP 骨架的識(shí)別與剪切效率飆升數(shù)十倍。

  通過建立這株穩(wěn)定轉(zhuǎn)染細(xì)胞，科研人員能在體外不需要借助原代神經(jīng)元的情況下，獲得一個(gè)能持續(xù)、高效、穩(wěn)定產(chǎn)生大量致病性 $\beta$-淀粉樣肽（A$\beta$）的細(xì)胞模式底盤。

• 核心表型與阿爾茨海默?。ˋD）生化特征：

  • 形態(tài)學(xué)改變：貼壁生長(zhǎng)。在倒置顯微鏡下，該細(xì)胞維持了親本 HEK293 的基本上皮樣（Epithelial-like）或多角形（Polygonal）形態(tài)。細(xì)胞常呈連續(xù)的成片貼壁生長(zhǎng)，胞間界限清晰。由于穩(wěn)定轉(zhuǎn)染了外源質(zhì)粒，日常培養(yǎng)中需利用特定的篩選抗生素（通常為 G418 / Geneticin）來維持其陽性克隆表型。

  • A$\beta$ 肽高豐度分泌特征：由于 Swedish 突變的存在，細(xì)胞內(nèi)部的淀粉樣變通路（Amyloidogenic pathway）占據(jù)絕對(duì)主導(dǎo)。在沒有外部刺激的狀態(tài)下，該細(xì)胞能將高水平的 APPsw 經(jīng) $\beta$-分泌酶（BACE1）和 $\gamma$-分泌酶連續(xù)剪切，源源不斷地向培養(yǎng)基上清中釋放高水平的致病性 A$\beta$40 和 A$\beta$42 寡聚體片段。

• 生物安全級(jí)別：1級(jí)（BSL-1）。

二 核心科研價(jià)值與轉(zhuǎn)化醫(yī)學(xué)應(yīng)用

HEK293-APP695 swedish 細(xì)胞因其極其穩(wěn)定的 A$\beta$ 分泌表型和易放大生產(chǎn)的特征，在神經(jīng)藥理學(xué)中擁有無可替代的地位：

1. 抗阿爾茨海默?。ˋD）創(chuàng)新小分子藥物的高通量體外篩選（HTS）：

   該細(xì)胞是全球各大藥企篩選 $\beta$-分泌酶抑制劑（BACE1 Inhibitors）、$\gamma$-分泌酶調(diào)節(jié)劑（GSMs）或抗 A$\beta$ 聚集天然藥物的黃金標(biāo)準(zhǔn)底盤?？蒲腥藛T通過將候選化合物與該細(xì)胞共培養(yǎng)，隨后通過 ELISA、HTRF（均相時(shí)差熒光）或 AlphaLISA 技術(shù)定量測(cè)定培養(yǎng)基上清中 A$\beta$40/A$\beta$42 的表達(dá)量跌幅，評(píng)估藥物的潛在靶向靶效。

2. APP 神經(jīng)內(nèi)吞、細(xì)胞內(nèi)運(yùn)輸與剪切降解機(jī)制探討：

   通過該模型，可以深入解構(gòu)高爾基體、內(nèi)體（Endosomes）以及溶酶體結(jié)構(gòu)中，APP 蛋白如何被轉(zhuǎn)運(yùn)、酸化并在何種亞細(xì)胞結(jié)構(gòu)中遭遇 BACE1 剪切。這對(duì)于尋找從源頭上阻斷 A$\beta$ 異常產(chǎn)生的分子通路至關(guān)重要。

3. 外源性 A$\beta$ 神經(jīng)毒性（Neurotoxicity）條件培養(yǎng)基制備：

   收集 HEK293-APP695 swedish 產(chǎn)生的富含 A$\beta$ 的條件培養(yǎng)基（Conditioned Medium），可以用于刺激小鼠原代神經(jīng)元、人誘導(dǎo)多能干細(xì)胞（iPSC）分化的神經(jīng)元或 PC12/SH-SY5Y 細(xì)胞。這被廣泛用于構(gòu)建體外神經(jīng)突觸退化、Tau 蛋白異常磷酸化和神經(jīng)元凋亡損傷模型。

三 實(shí)驗(yàn)室細(xì)胞復(fù)蘇、貼壁常規(guī)培養(yǎng)、傳代與保存標(biāo)準(zhǔn)步驟

HEK293-APP695 swedish 細(xì)胞增殖迅速，貼壁較輕，對(duì)機(jī)械剪切力相對(duì)敏感。在培養(yǎng)和傳代中，最大的控制核心是把控篩選抗生素（G418）的加藥窗口，并防止細(xì)胞過度生長(zhǎng)而導(dǎo)致整片脫落。

1. 培養(yǎng)基配置與抗生素壓力維持

• 基礎(chǔ)培養(yǎng)基：高糖 DMEM 培養(yǎng)基。

• 完全培養(yǎng)基配方（日常擴(kuò)增）：高糖 DMEM 基礎(chǔ)培養(yǎng)基 加 10% 優(yōu)質(zhì)胎牛血清（FBS） 加 1% 青霉素-鏈霉素雙抗。

• 陽性克隆選擇壓力（關(guān)鍵點(diǎn)）：

  • 在常規(guī)擴(kuò)增與日常傳代期間，完全培養(yǎng)基中必須常規(guī)添加維持劑量的 G418 抗生素（根據(jù)具體克隆來源和批次說明，常規(guī)維持濃度通常在 200 $\mu$g/mL - 400 $\mu$g/mL 左右），以維持其外源 APP695 swedish 基因的穩(wěn)定表達(dá)，防止隨著傳代發(fā)生質(zhì)粒丟失。

  • 重要提示：在正式用于下游實(shí)驗(yàn)（如收集培養(yǎng)基上清進(jìn)行 A$\beta$ 的 ELISA 檢測(cè)、Western Blot 蛋白分析或進(jìn)行細(xì)胞毒性測(cè)試）前，建議更換為不含 G418 的常規(guī)完全培養(yǎng)基進(jìn)行洗脫，以清除抗生素本身對(duì)下游生化指標(biāo)或活細(xì)胞生理狀態(tài)的干擾。

• 細(xì)胞解離液：0.25% Trypsin-0.02% EDTA 消化液（由于該細(xì)胞貼壁較輕，也可使用不含胰酶的溫和解離液或直接用 PBS 輕輕吹打脫落）。

• 環(huán)境參數(shù)：37 攝氏度，5% 二氧化碳，飽合濕度環(huán)境。

2. 冷凍細(xì)胞復(fù)蘇步驟

1. 提前在無菌生物安全柜中配制好干凈的 T25 培養(yǎng)瓶，注入 5 - 6 mL 預(yù)熱至 37 攝氏度的常規(guī)完全培養(yǎng)基（注意：復(fù)蘇第一代時(shí)，為了讓受損細(xì)胞順利恢復(fù)貼壁，千萬不要添加 G418 藥物）。

2. 從液氮罐中取出凍存管，立刻全量投入 37 攝氏度恒溫水浴箱中快速搖晃解凍，確保在 1 分鐘內(nèi)令管內(nèi)冰塊完全融化。

3. 用 75% 酒精噴灑外壁消毒，隨后移入生物安全柜。

4. 用無菌移液槍吸取融化的細(xì)胞懸液，緩慢滴加至盛有 4 mL 預(yù)熱常規(guī)完全培養(yǎng)基的 15 mL 離心管中，輕柔顛倒一次以稀釋冷凍保護(hù)劑（DMSO）。

5. 以 1000 rpm（約 200 g）離心 4 - 5 分鐘，小心吸除含有二甲基亞砜（DMSO）的上清液。

6. 加入 1 - 2 mL 新鮮常規(guī)完全培養(yǎng)基重懸細(xì)胞沉淀，將其接種至準(zhǔn)備好的 T25 瓶中。前后輕柔十字晃動(dòng)混勻，置于孵箱中。

7. 復(fù)蘇 24 小時(shí)后，在顯微鏡下常規(guī)觀察細(xì)胞貼壁展弦狀態(tài)。由于復(fù)蘇時(shí)未加選擇抗生素，此時(shí)應(yīng)進(jìn)行一次全量更換新鮮完全培養(yǎng)基的操作。待細(xì)胞完全貼壁并進(jìn)入對(duì)數(shù)生長(zhǎng)狀態(tài)（通常復(fù)蘇 2 天后），在下一次傳代時(shí)再重新加入含維持劑量 G418 的完全培養(yǎng)基。

3. 日常貼壁常規(guī)傳代操作

• 傳代時(shí)機(jī)：當(dāng)細(xì)胞融合度達(dá)到 80% - 90%（即上皮樣細(xì)胞密集對(duì)接，但尚未完全重疊擠壓）時(shí)必須進(jìn)行傳代。HEK293 的衍生株細(xì)胞若達(dá)到 100% 極度過密狀態(tài)，細(xì)胞會(huì)自發(fā)向上層疊堆積，導(dǎo)致下層細(xì)胞因接觸抑制和缺氧發(fā)生成片成大塊的自發(fā)脫落。

• 操作流程：

  1. 吸除細(xì)胞瓶?jī)?nèi)的舊培養(yǎng)基，使用無菌的、不含鈣鎂離子的 PBS 緩沖液輕輕漂洗細(xì)胞表面 1 次。(注：由于 HEK293 衍生細(xì)胞貼壁較輕，加入 PBS 時(shí)務(wù)必靠著不長(zhǎng)細(xì)胞的瓶壁緩慢注入，切勿直接正對(duì)著細(xì)胞層猛烈噴淋，防止細(xì)胞被非特異性洗脫)。

  2. 加入適量 0.25% 胰酶消化液（T25 瓶常規(guī)加入 1 mL），輕搖使其完全覆蓋細(xì)胞層。置于 37 攝氏度孵箱（或直接在室溫下）消化 1 - 2 分鐘。

  3. 在倒置顯微鏡下進(jìn)行實(shí)時(shí)動(dòng)態(tài)觀察。由于其對(duì)胰酶高度敏感，當(dāng)看到多角形細(xì)胞體邊緣回縮變圓、胞間裂隙增大、輕敲瓶壁可見大面積細(xì)胞滑落時(shí)，立刻加入 2 到 3 倍體積的含血清完全培養(yǎng)基以終止胰酶的解離反應(yīng)。

  4. 用移液槍在瓶壁輕輕吹打數(shù)次，使其徹底剝離并盡可能打散形成均勻的單細(xì)胞懸液。收集入管，1000 rpm 離心 5 分鐘。

  5. 棄去上清，加入含維持劑量 G418 的完全培養(yǎng)基重懸。按照 1 比 4 至 1 比 6 的常規(guī)稀釋比例，接種至新的培養(yǎng)瓶中。通常每 2 - 3 天傳代一次。

4. 細(xì)胞長(zhǎng)期保存標(biāo)準(zhǔn)

• 凍存液配方：90% 優(yōu)質(zhì)完全培養(yǎng)基（無 G418） 加 10% 分析級(jí)二甲基亞砜（DMSO）。

• 冷凍規(guī)范：

  1. 收集處于對(duì)數(shù)生長(zhǎng)最旺盛期、健康指數(shù)高、融合度在 80% 左右、未發(fā)生空泡化衰老的 HEK293-APP695 swedish 細(xì)胞（處于加藥維持狀態(tài)的細(xì)胞即可）。

  2. 經(jīng)溫和消化、離心沉淀后，用配置好的無藥凍存液懸浮，調(diào)整細(xì)胞密度至 每毫升 1,500,000 到 3,000,000 個(gè)細(xì)胞。

  3. 分裝入無菌凍存管中，立刻移入標(biāo)準(zhǔn)程序降溫盒（如 Mr. Frosty），并置于 零下 80 攝氏度冰箱中過夜梯度降溫（遵循約每分鐘降溫 1 攝氏度的穩(wěn)態(tài)速率）。

  4. 次日，必須迅速將凍存管轉(zhuǎn)移入液氮罐（零下 196 攝氏度）長(zhǎng)期鎖死保存。絕對(duì)禁止在 零下 80 攝氏度普通冰箱內(nèi)長(zhǎng)期存放，以防微小的溫度震蕩導(dǎo)致細(xì)胞內(nèi)部冰晶重組，進(jìn)而嚴(yán)重惡化后續(xù)復(fù)蘇時(shí)的貼壁存活率與特殊的基因穩(wěn)定表達(dá)譜。

Part 2 English Section

I General Information and Cell Biological Background

• Cell Line Name: HEK293-APP695 swedish (Standardly referenced as HEK293-APPsw, HEK293/APP695swe, or HEK293-Swedish).

• Organism and Tissue Extraction Origin: Homo sapiens (human); derived from the Human Embryonic Kidney 293 (HEK293) parental reference line, engineered via molecular cloning to stably express human amyloid precursor protein (APP695) harboring the Swedish mutation.

• Cell Line Establishment Background (Standard In Vitro Alzheimer's Disease Model):

  The HEK293 platform is a standard baseline chassis across global pharmacological and neuroscientific laboratories due to its exceptional exogenous protein expression efficiency, clean genomic backdrop, and robust adherent propagation kinetics.

  APP695 is the predominant full-length amyloid precursor protein splice isoform expressed within the human brain and central nervous system. The Swedish mutation represents a classic, highly penetrant familial Alzheimer's disease (FAD) genetic anomaly characterized by a double-nucleotide substitution at the $\beta$-secretase cleavage boundary, substituting K670N / M671L (Lys670Asn / Met671Leu) within the amino acid sequence. This alterations drives a multifold surge in the recognition and cleavage efficiency of APP by endogenous $\beta$-secretase.

  By locking in this stable transfectant, investigators possess a continuous, uniform human model that robustly generates neurotoxic $\beta$-amyloid (A$\beta$) peptides without requiring primary neuronal isolation.

• Core Morphological Phenotype and Alzheimer's Disease (AD) Biomarkers:

  • Morphological Form: Adherent growth; under inverted phase-contrast microscopy, it preserves the classic epithelial-like or polygonal architecture of the parental HEK293 lineage, expanding in continuous monolayers. To ensure the integrity of the transfectant plasmid framework, cultures are standardly maintained under continuous selective antibiotic pressure (typically G418 / Geneticin).

  • Hyper-Secretory A$\beta$ Biomarker Matrix: Driven by the Swedish structural mutation, intracellular proteolytic sorting is heavily steered toward the amyloidogenic pathway. Under baseline propagation parameters, the cell line continuously processes exogenous APPsw via coordinated $\beta$-secretase (BACE1) and $\gamma$-secretase cleavage cascades, continuously shedding significant titers of neurotoxic A$\beta$40 and A$\beta$42 oligomeric fragments directly into the culture supernatant.

• Biosafety Matrix: Classified under Biosafety Level 1 (BSL-1) containment parameters.

II Strategic Research Value and Translational Fields

Because of its reproducible A$\beta$ secretory profiles and easily scaled expansion traits, HEK293-APP695 swedish is widely used in neuropharmacological discovery:

1. High-Throughput Screening (HTS) of Advanced Anti-AD Therapeutics:

   The line operates as a gold-standard bioassay platform across global pharmaceutical screens to evaluate the potency of novel $\beta$-secretase inhibitors (BACE1 inhibitors), $\gamma$-secretase modulators (GSMs), and small molecules targeting A$\beta$ aggregation networks. Co-incubating candidate chemical structures with this line allows direct quantification of A$\beta$40/A$\beta$42 titers in the supernatant via ELISA, HTRF, or AlphaLISA arrays to determine target validation.

2. Mapping APP Endocytosis, Intracellular Transport, and Proteolytic Processing:

   This system is utilized to map how APP molecules navigate through the Golgi network, endosomes, and lysosomal tracks, pinpointing exactly where BACE1 cleavage occurs. Resolving these trafficking pathways aids in discovering mechanisms to intercept pathogenic processing loops.

3. Harvesting High-Titer A$\beta$-Rich Conditioned Medium for Neurotoxicity Profiling:

   The culture supernatant generated by HEK293-APP695 swedish cells can be harvested as a standardized source of A$\beta$-rich Conditioned Medium (CM). This medium is deployed to treat primary murine cortical neurons, human iPSC-derived neuronal networks, PC12, or SH-SY5Y cultures, providing a reliable baseline for analyzing synaptic regression, pathologic Tau hyperphosphorylation, and neuronal apoptotic dynamics.

III Laboratory Thawing, Cultivation, Passaging, and Cryopreservation Protocols

HEK293-APP695 swedish cells proliferate with rapid doubling cycles and display light surface attachment parameters, making them sensitive to abrupt fluid shear forces. Daily subculturing requires careful regulation of G418 antibiotic selection windows and subconfluent passaging controls to avoid sheet detachment.

1. Growth Medium & Selection Antibiotic Maintenance Protocols

• Basal Medium: High-glucose DMEM medium.

• Maintenance Complete Medium Formulation (Routine Expansion): Basal high-glucose DMEM medium enriched with 10% premium Fetal Bovine Serum (FBS) and fortified with 1% standard Penicillin-Streptomycin dual antibiotics.

• Selection Pressure Control Window (Critical Quality Parameter):

  • During standard expansion and routine passaging routines, the complete growth medium must be spiked with a maintenance dose of G418 antibiotic (ranging standardly between 200 $\mu$g/mL and 400 $\mu$g/mL depending on specific lot verification thresholds) to prevent plasmid loss and genetic regression over continuous generation cycles.

  • Critical Operational Note: The selection medium must be evacuated and replaced with G418-free complete growth medium prior to initiating functional assays (such as harvesting supernatant fractions for downstream A$\beta$ ELISA metrics, Western blot assays, or target cell toxicity exposures) to eliminate background antibiotic interference with cellular health indicators.

• Cell Dissociation Enzyme: Standard 0.25% Trypsin-0.02% EDTA solution (due to light attachment traits, gentle non-enzymatic dissociation buffers or direct gentle PBS flushing can also be deployed).

• Environmental Cultivation Constants: Incubate at 37 degrees Celsius inside a humidified atmosphere charged with 5% Carbon Dioxide.

2. Cryovial Thawing and Recovery Sequence

1. Pre-warm a pristine T25 tissue culture flask filled with 5 - 6 mL of standard G418-free complete growth medium inside the Class II Biosafety Cabinet. (Note: Do not add selection antibiotics during the initial 24-hour post-thaw recovery phase to maximize cell attachment and safeguard fragile membranes).

2. Retrieve the cryovial from liquid nitrogen storage and submerge it instantly into a 37 degrees Celsius constant-temperature water bath. Shake rapidly and continuously to secure absolute thawing within 60 seconds.

3. Decontaminate the exterior shell with 75% ethanol before transfer into the biosafety station.

4. Using a sterile pipettor, smoothly extract the thawed suspension and deliver it dropwise into a 15 mL conical tube packed with 4 mL of pre-warmed drug-free complete medium, inverting gently once to equalize osmotic pressures.

5. Centrifuge the suspension at 1000 rpm (approximately 200 g) for 4 - 5 minutes at room temperature, then carefully decant the DMSO-laden supernatant.

6. Resuspend the cell sediment in 1 - 2 mL of fresh drug-free complete growth medium, transfer the entire volume into the prepared T25 flask, cross-shake smoothly to optimize seeding distribution, and place in the incubator.

7. Inspect the adherent status approximately 24 hours post-thaw. Perform a complete medium change using pre-warmed complete medium to clear non-adherent dead cell fragments and residual DMSO. Once the cells regain robust log-phase division metrics (typically 2 days post-thaw), reintroduce the complete growth medium spiked with the selection dose of G418 at the next passage.

3. Routine Adherent Passaging Mechanics and Maintenance

• Confluency Control Window: Subculturing routines must be initiated when monolayers achieve an optimal 80% - 90% confluency scale. Because HEK293 lines exhibit light attachment, allowing sheets to hit absolute 100% full saturation or overgrowth forces cells to pile up vertically, leading to large-scale detachment into floating sheets.

• Passaging Execution Steps:

  1. Aspirate the spent growth matrix and gently rinse the cell layer once with sterile, calcium/magnesium-free PBS. Note: Always deliver the PBS slowly against the empty interior flask wall opposite the cell layer, never directly onto the monolayer, to prevent unintended cell washing or loss due to light attachment.

  2. Administer a suitable volume of 0.25% Trypsin-EDTA enzyme (typically 1 mL for a T25 flask format), tilt the flask to ensure total monolayer coverage, and place inside the 37 degrees Celsius incubator (or hold at room temperature) for 1 - 2 minutes.

  3. Monitor cell detachment kinetics under an inverted microscope. As the cells round up, separate from neighbors, and slide upon gentle physical tapping of the flask wall, immediately add 2 to 3 volumes of serum-fortified complete growth medium to arrest enzymatic cleavage.

  4. Gently pipette the solution against the flask walls to rinse down remaining cells and dissociate clusters into a single-cell suspension. Transfer the suspension into a conical tube and centrifuge at 1000 rpm for 5 minutes.

  5. Discard the supernatant, resuspend the cell pellet in fresh, pre-warmed complete growth medium supplemented with the maintenance dose of G418, and inoculate into new flasks utilizing standard split ratios of 1:4 to 1:5. Subculture every 2 - 3 days.

4. Long-Term Cryopreservation Standards

• Cryoprotectant Preservation Matrix: 90% premium complete growth medium (without G418) supplemented with 10% analytical-grade Dimethyl Sulfoxide (DMSO).

• Freezing Protocol Validation:

  1. Exclusively harvest healthy, log-phase cultures showing an optimal confluency of approximately 80% under standard maintenance selection criteria.

  2. Post-enzymatic treatment and centrifugation, adjust the cell concentration inside the formulated drug-free cryoprotectant matrix to a target range of 1,500,000 to 3,000,000 cells per milliliter.

  3. Dispense the suspension into sterile cryovials, insert them immediately into a controlled-rate freezing device (e.g., Mr. Frosty), and place into a minus 80 degrees Celsius freezer overnight to achieve steady gradient cooling (approximately 1 degree Celsius per minute).

  4. The following day, swiftly transfer the frozen cryovials into liquid nitrogen storage tanks (minus 196 degrees Celsius) for definitive long-term preservation. Do not store vials indefinitely inside a minus 80 degrees Celsius freezer; minor temperature oscillations over extended periods can compromise post-thaw recovery rates and lead to plasmid instability.

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